Former senator Kay Hagan (D-N.C.), who lost her seat in November, is seen as a potential candidate in 2016. (Ted Richardson/For The Washington Post)

The war hero. The star fundraiser. The popular governor. The toughened ex-senators.

These are the blue-chip recruits many Democrats believe are essential to winning back control of the U.S. Senate in 2016 after a midterm drubbing cost them their majority.

Less than four months after the painful losses, Democratic officials have begun charting a path back to Senate control that runs through more than half a dozen blue and purple states where the presidential campaign is expected to boost Democratic turnout. But even in that favorable terrain, the party faithful fear they could fall short if marquee challengers don’t step forward, since their talent pool is shallow and they are trying to unseat a well-prepared group of Republican senators.

“The bench is short, but the aces are strong,” said Democratic donor John Morgan. He summed up the all-or-nothing outlook with another baseball analogy: “All you need is a right-hander that throws 99 mph, and you don’t need a bench.”

Needing to gain four seats — five if a Republican wins the White House — to reclaim the majority, Democrats are under intense pressure to enlist top contenders. Since House Republicans hold their widest majority in decades and are early favorites to stay in power, the fight for the Senate stands to determine whether the next president will face a split Congress or one controlled completely by the GOP.

New Hampshire Gov. Maggie Hassan, who was reelected in a strong year for Republicans, could be the Democrats’ challenger to Sen. Kelly Ayotte (R) next year. (Jim Cole/AP)

“Candidates matter,” said former Pennsylvania governor Edward G. Rendell (D). “The lesson of 2010 is that even in the wave election, where Republicans nominated candidates with flaws, they lost. So we can’t just nominate anybody. We’ve got to find really good candidates.”

Interviews with more than a dozen state-based and national Democrats revealed an early wish list headlined by well-known former Ohio governor Ted Strickland; Rep. Tammy Duckworth (Ill.), a decorated Iraq war veteran who lost her legs during a combat mission; popular New Hampshire Gov. Maggie Hassan; former senator Russell Feingold (Wis.), a liberal favorite; Rep. Patrick Murphy (Fla.), a talented fundraiser from a swing district; and former senator Kay Hagan (N.C.), who lost a close reelection race.

None have ruled themselves in or out. They will be closely watched in the coming months, with some Democrats already fretting about recruiting at a time when recent down-ballot losses have thinned the ranks of promising prospects.

“I’m worried, of course,” said Peter Buttenwieser, a longtime Democratic donor. “But on the other hand, I have confidence that when the time for the ballgame rolls around, we will have those kinds of people.”

Democratic Senatorial Campaign Committee officials declined to discuss which possible challengers the committee is looking at and dismissed suggestions that they can’t win back the Senate without landing recruits who have run statewide before. Their message: It’s early.

“What we are doing right now is we are contacting folks in the states that know the states,” said Sen. Jon Tester (Mont.), the new DSCC chairman. He predicted that the political environment will turn in favor of Democrats as 2016 draws closer, enticing top candidates to run.

But already, there are concerns in the party about what happens if they don’t.

“I wish we had a stronger bench, no doubt about that,” Buttenwieser said.

Map favors Democrats

Republicans will be defending 24 Senate seats in 2016, seven in states that President Obama won twice. Democrats will defend only 10, all in states that Obama carried in both 2008 and 2012.

The possibility of running alongside Hillary Rodham Clinton, the presumed Democratic front-runner for president, in states she would be expected to contest could entice top-flight Democrats to enter the fray, strategists say.

“The calculus has to be that ’16 provides a better path for you because you’ve got a demographic electorate that just shapes up better for Democrats,” said Steve Schale, a Florida-based Democratic strategist.

But Democrats say they cannot rely on presidential coattails alone. They face a group of well-funded, likable Republican senators who will have the full backing of the GOP.

“We are going to run as hard and as scared as possible in every race we have,” said Kevin McLaughlin, deputy executive director of the National Republican Senatorial Committee.

Democrats’ best pickup chances are in the neighboring states of Wisconsin and Illinois, according to strategists and observers. Sens. Ron Johnson (Wis.) and Mark Kirk (Ill.) won their seats in the 2010 GOP wave. They are expected to face more liberal electorates in 2016.

To the east are three more top first-term Republican targets — Sens. Rob Portman (Ohio), Pat Toomey (Pa.) and Kelly Ayotte (N.H.) — along with second-term Sen. Richard Burr (N.C.). Democrats are also pursuing the seat of Sen. Marco Rubio (Fla.), who appears to be moving toward a White House run, not a reelection campaign.

A Republican has not won a presidential election in Illinois since 1988. In Wisconsin, the GOP drought extends to 1984. That makes Johnson and Kirk — the latter won by fewer than 60,000 votes in 2010 — ripe targets next year.

Wisconsin could feature a rematch of 2010, when Johnson unseated Feingold. Feingold’s loyalty among the state’s sizable base of liberal voters makes him an attractive choice in the eyes of many Democrats. But after Feingold, there is no consensus candidate.

Other names mentioned in Democratic circles include Rep. Ron Kind, a more conservative Democrat who lacks Feingold’s star power, and former Trek executive Mary Burke, who just lost the governor’s race.

In Illinois, Kirk, who returned to the Senate in 2013 less than a year after suffering a stroke, is gearing up for his reelection campaign. Duckworth, his possible challenger, is a rising national star who also has a compelling personal story about overcoming serious adversity. She is a former Army helicopter pilot who was awarded a Purple Heart after losing her legs during a 2004 mission in Iraq.

“I think if it’s not Tammy, you have a very wide-open Democratic primary,” said Illinois-based Democratic strategist Eric Adelstein.

Rep. Bill Foster (D), who is one of the wealthiest members of Congress and could self-fund a campaign, is another possible candidate.

Portman and Toomey present tougher challenges for Democrats. Their states have been more competitive in presidential elections, they have well-stocked campaign accounts, and they have carefully avoided being cast as polarizing figures in their purple states.

“Senator Toomey has done a good job politically. I think he strengthened his position in the Philadelphia suburbs with his leadership on the gun issue,” Rendell said, referring to Toomey’s 2013 push to expand background checks in gun sales.

Former congressman Joe Sestak (D), who lost to Toomey in 2010, is planning to run again. But strategists expect that he will have company in the primary.

Speculation has flared in Ohio over the possibility of former governor Strickland challenging Portman. The Democrats’ need for Strickland, who is seen as the top get, grew last week when Rep. Tim Ryan (D), another capable potential challenger, said he would not run. Cincinnati City Councilman P.G. Sittenfeld is the only other Democrat in the race right now.

In New Hampshire, Hassan is the clear top prize. The governor is fresh off winning a second two-year term in a very strong year for Republicans. Democrats don’t expect her to make a decision until after the state legislative session wraps up later this year. But Hassan has the potential to effectively clear the primary field and allow Democrats to focus on Ayotte, who like Toomey and Portman has avoided being seen as a bomb-thrower.

North Carolina, site of the most expensive and arguably the nastiest Senate race of 2014, could host another explosive contest in 2016. Hagan, who lost by about two percentage points, is viewed as a ready-made candidate whose ability to swiftly raise heaps of cash could put pressure on Burr.

Hagan’s campaign manager, Preston Elliot, is now deputy executive director of the DSCC.

Another possibility Democrats mentioned for North Carolina is the state treasurer, Janet Cowell. But as in other states the party is targeting, the drop-off between the first and second tier is steep.

“We don’t have a deep bench. Not a lot of high-profile people,” said Thomas Mills, a North Carolina Democratic strategist and blogger.

In Florida, the big question is whether Rubio will forgo a reelection bid for a White House run, as many expect.

Either way, Murphy, who is weighing a campaign, is considered a top choice in yet another state with few standout prospects. Just 31, Murphy represents a swing district and raised more than $5 million in the last election cycle, a hefty sum for a House candidate.

Vulnerable incumbents

While the presidential election is the top priority, the desire to break the GOP’s dominance on Capitol Hill by 2017 is Task 1-A for Democrats.

“We need a Democratic Senate to work with what I see [will be] a Democratic president,” said Jim Manley, a former aide to Senate Minority Leader Harry M. Reid (D-Nev.).

Democrats are under even more pressure to find top candidates in states where they are on offense, because they are at risk of losing some of their own seats. In Colorado, Sen. Michael F. Bennet could face a tough challenge. In Nevada, Reid is actively preparing for a reelection campaign, even as he is recovering from eye surgery, and even though it’s not 100 percent clear that he will run.

Republicans say they will compete hard for Nevada, regardless of what Reid does. Gov. Brian Sandoval is widely seen as the most formidable Republican who might run.

“Harry Reid is the single most vulnerable senator in the United States of America,” the NRSC’s McLaughlin said.

In California, a heavily Democratic state, the Senate race is already taking shape. Sen. Barbara Boxer’s retirement announcement last month quickly spurred a host of up-and-coming fellow Democrats to take a look at running. State Attorney General Kamala Harris, a rising star, recently entered the race and won the backing of Sen. Elizabeth Warren (D-Mass.). Harris is regarded as the early front-runner.

Not all of the most successful Senate recruits in recent years have come from the big-name talent pool. One of the standouts of 2014 was Iowa Republican Joni Ernst, a little-known state senator before she won her seat. Ernst is now building a national profile: She recently delivered the Republican response to Obama’s State of the Union address.

But Democrats are not content to count on surprise successes, with the still-fresh sting of the midterms fueling a desire to dust themselves off quickly.

“We took pretty much a shellacking last November, so we’ve got to a do much better job if we are going to retake the Senate in 2016,” Manley said.