The tea party's 2014 window is closing -- quickly.

(Bill O’Leary/The Washington Post)

After a series of recruiting failures and defeats in Texas, Kentucky, North Carolina and Georgia this primary season, tea party candidates for U.S. Senate are looking at a very limited slate of remaining primaries in which they can realistically hope for big victories this year.

Their last best chance may be in Mississippi on June 3. State Sen. Chris McDaniel (R), the darling of national tea party groups, has a chance of knocking off longtime Sen. Thad Cochran (R), an avid appropriator who is just the kind of Republican the tea party likes to try to dislodge.

But the race has been roiled by a string of arrests related to the photographing of Cochran's bedridden wife. At least two of the men arrested are McDaniel supporters, though McDaniel says he is not involved at all. Even so, the story hasn't helped him. Instead of talking about Cochran's record, everyone's talking about the Cochran case.

South Carolina's primary is June 10. But despite all the chatter about taking down Sen. Lindsey Graham (R-S.C.), none of his tea party challengers has emerged as real threats.

An open Senate primary in Oklahoma on June 24 presents a better opportunity than South Carolina for the tea party -- but it's hardly a sure bet. Former state House speaker T.W. Shannon (R) -- whom Sen. Ted Cruz (R-Tex.) backed with his first contested Senate primary endorsement -- is in a competitive race against Rep. James Lankford (R), whom national tea party groups don't like.

August will mark the end of primary season in Kansas and Tennessee, where Sens. Lamar Alexander (R-Tenn.) and Pat Roberts (R-Kan.) looked like potentially ripe targets earlier this cycle. But physician Milton Wolf (R) hasn't gotten that much traction against Roberts, and Alexander's opponents aren't real threats at this point.

Stung by tough primary losses by Republicans Sens. Richard Lugar and Robert Bennett in 2012 and 2010, incumbents are striking back this cycle with more diligent preparation, better opposition research and more active outreach to tea party activists. Just ask Mitch McConnell and John Cornyn, the top two Republicans in the Senate. Both were considered vulnerable this cycle. Both avoided tough primary campaigns by pivoting right and spending big.

The silver lining for the tea party in what's shaping up as a tough cycle in the battle for the Senate may be that they are pushing establishment Republicans to take more conservative positions.

"The overall trend is undeniably conservative, even establishment-backed candidates are running as conservatives," said Keith Appell, a conservative strategist. "How they eventually govern, if elected, may be an open question. But they're on record with voters as taking strong conservative stands, and voters will expect them to back up their statements with actions."

But wins still matter. And so far this cycle, the GOP establishment is racking up more W's than the tea party.

And now, to our latest rundown of the top 11 Senate races most likely to change party control. As always, No. 1 is the seat most likely to flip.

To the Line!

10. Georgia (Republican-controlled) and Michigan (Democratic-controlled): Republicans got the best possible outcome in the Peach State on Tuesday when Rep. Jack Kingston and businessman David Perdue advanced to a GOP runoff. That's bad news for Democrat Michelle Nunn because they have long been viewed as the two strongest general election candidates. We're leaving Georgia on the Line for now, because Nunn has continued to poll well, and Kingston and Perdue are about to engage in a nasty fight. Still, Republicans are in the driver's seat, and Nunn has yet to feel the full force of Republican attacks. In Michigan, there's hasn't been much new polling since our last round of rankings, when surveys had shown a competitive race between Rep. Gary Peters (D) and former secretary of state Terri Lynn Land (R). (Previous rankings: 9)

9. Colorado (D): An April Quinnipiac University poll showed a dead heat between Rep. Cory Gardner (R) and Sen. Mark Udall (D). Gardner's 11th-hour bid and quick clearing of the GOP field created a big headache for Democrats. But Gardner's now going to need to contend with a barrage of attacks from environmental groups. The League of Conservation Voters has already started its assault. Billionaire climate activist Tom Steyer is next. (Previous ranking: 10)

8. Alaska (D): This is the one race where we can say with near certitude that Democrats are not going to get outspent by Republicans in a big way. Why? Because it's so cheap. Groups from both parties have been rushing to reserve fall air time like in no other race. That gives Sen. Mark Begich an advantage some of his fellow vulnerable Democratic senators do not have. His likely GOP opponent is former attorney general Dan Sullivan, who has been rounding up support from both conservative and establishment Republicans. (Previous ranking: 7)


7. Kentucky (R): Businessman Matt Bevin (R) was no match for Mitch McConnell, but Secretary of State Alison Lundergan Grimes (D) is a different story. This is going to be one of the most expensive -- also probably one of the nastiest -- races on the map this cycle. The national environment plays into McConnell's hands and spells trouble for Grimes if Republicans can successfully tie her to President Obama's agenda. But McConnell's lingering unpopularity back home means if Grimes can make this a local race, she'll have a chance. (Previous ranking: 8)

6. Arkansas (D): Recent polling has shown that Sen. Mark Pryor (D) may not be nearly as vulnerable as many had believed him to be. The presence of so many competitive races for Democrats -- including two U.S. House races and the race for governor --  and the prospect of the popular Bill Clinton stumping for the party at home has raised optimism about Pryor defeating Rep. Tom Cotton (R). (Previous ranking: 5)

5. North Carolina (D): Republican Thom Tillis's win in the Republican primary sans runoff was just what the GOP needed. Now, Republicans can focus all their attention on Sen. Kay Hagan (D). Whereas air time is cheap in sparsely populated Alaska, it's expensive in the many media markets of the Tar Heel State. If Republican groups keep up their torrid spending pace here, it will spell bad news for Hagan. (Previous ranking: 6)

4. Louisiana (D): As The Post's Aaron Blake noted last week, the most important polls to pay attention to are the head-to-head matchups between Sen. Mary Landrieu (D) and Rep. Bill Cassidy (R), since the race will head to a runoff if no candidate wins a majority in the all-party November primary. Even Democratic polling shows a dead-even Landrieu-Cassidy matchup. (Previous ranking: 4)

3. Montana (D): Rep. Steve Daines (R) and Sen. John Walsh (D) each released deeply personal ads involving women this week. Walsh's commercial featured a woman who says she was raped; Daines released one with a woman who said she suffered domestic violence. Both candidates are making a pitch for female voters in a race that still appears to tilt toward the Republicans. (Previous ranking: 3)

2. West Virginia (D): Secretary of State Natalie Tennant (D) challenged Rep. Shelley Moore Capito (R) to five televised debates as soon as the primaries ended. But Tennant will probably need some momentum-shifting moments to score an upset in a state where President Obama and the national Democratic Party are deeply unpopular. (Previous ranking: 2)

1. South Dakota (D): Former Tom Daschle aide Rick Weiland (D) was the second major Democratic Senate candidate to call for the resignation of Veterans Affairs Secretary Eric K. Shinseki over the scandals at the VA. Weiland's doing all he can right now, but make no mistake: Former governor Mike Rounds (R) is a heavy favorite. (Previous ranking: 1)