Mitch McConnell’s political life used to be a lot easier before he became one of the most powerful leaders in the Republican Party.

Before he became Senate minority leader, McConnell (Ky.) cruised to reelection victories with relatively big margins in 1996 and 2002, with little national attention. Today he finds himself in a dead-heat contest against a relative newcomer in what could be the most expensive race in the country. And he knows why.

“The new paradigm, if you’re the leader of one of the parties these days, is that in all likelihood you’re the only Senate candidate in the country that every — in my case — crazy liberal on the other side has heard of,” McConnell told GOP activists at Graves County High School early last month as he stumped for a sixth term.

The dire implications of that new order is that it is now much easier for opponents to turn Washington leaders into national political villains, yielding campaign money from partisans all across the country.

The influence that once rendered the most powerful Washington figures practically immune from tough elections now makes them bigger targets, easy political prey. The targeting of Senate party leaders has come to resemble a long-running Mafia war in which rival families are constantly trying to take out the other’s don.

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The practical result, veteran lawmakers say, is that the current dons — Majority Leader Harry M. Reid (D-Nev.) and McConnell — spend a lot of time and effort trying to outmaneuver each other, always cognizant about how each vote will play out on the campaign trail. The result is gridlock.

Now, it’s personal

In June and July, the legislative agenda ground to a halt in the Senate as McConnell repeatedly tried to attach a pro-coal amendment to any bill that moved, forcing Reid to not move any bills that would force vulnerable Democrats from casting a tough vote. Reid is also determined to deny McConnell any victory that would help his reelection effort in coal-producing Kentucky.

Senate leaders do not expect to get a free pass in their reelections, and many senators contend that tough races help keep those with lofty titles in tune with real voters. But many veteran senators are dismayed at how personal these campaigns have become for two leaders who have to work together, and there is a growing sense that the tactics have crossed the line.

Many connect the state of affairs to a decision 10 years ago by Sen. Bill Frist (R-Tenn.), then the majority leader, to recruit and then campaign for a challenger to Sen. Thomas A. Daschle (D-S.D.), then the minority leader. Democrats see it as a defining moment that still echoes through the Senate.

“I think it was the beginning of the breakdown of comity and bipartisanship. I really do,” Sen. John D. Rockefeller IV (D-W.Va.) said in an interview.

Retiring after 30 years in the Senate, Rockefeller said he has spent much time recently reflecting on today’s partisanship and keeps circling back to 2004.

“I’ve been thinking about that,” he said. “I really think that was the difference. It was so shocking to do that. It was so specific. It was like a targeted drone strike.”

Eight weeks out from Election Day, Chris Cillizza breaks down where each party stands in the fight for control of the Senate. Hint: It's very close. (Jeff Simon/The Washington Post)

After Daschle lost his reelection bid 2004, Democrats in 2008 went after McConnell, who tripled his own campaign spending to win a close race. Republicans returned the favor in 2010 by nearly knocking off Reid, who is now actively helping McConnell’s opponent, Alison Lundergan Grimes. Reid can expect to be a top target if he decides to seek reelection in 2016.

In the nearly 35 years before Daschle’s 2004 race, every Senate leader who stood for reelection won in a landslide. That era is now a distant memory. McConnell’s 2014 race marks the fourth time in the past six elections in which a Senate leader is battling for survival, and Reid would make it five elections out of seven should he run again.

The first blow

In May 2004, 20 miles east of Rapid City, S.D., Frist made the aggressive move to campaign in Daschle’s home state alongside John Thune, the young Republican who became the first challenger to unseat a sitting Senate leader since 1952. It shocked the political sensibilities in Washington.

But Frist was a deeply frustrated leader with the slimmest of majorities, and Daschle was a constant foil. Frist told South Dakota voters that the best chance they had to save Ellsworth Air Force Base from closure was to throw out the minority leader and vote for Thune. “It may be rare, but these are rare times,” he conceded.

What was then rare is now just considered the first big shot in an ever-escalating war.

Back then the George W. Bush White House grew furious at Democratic legislative tactics, particularly Daschle’s decision to lead the filibuster of more than a handful of Bush’s nominations to federal appeals courts. Just two years earlier, when Frist ran the Senate GOP’s campaign operation, Thune narrowly lost to Sen. Tim Johnson (D-S.D.) in what Republicans turned into a proxy fight against Daschle. So in 2004 they decided to take the fight right to the minority leader, who was well liked but could not hold off Thune in a conservative state that gave Bush a 28-point margin in his 2004 reelection. Reid then succeeded Daschle as Democratic leader.

Frist retired at the end of 2006 as voters handed Democrats a Senate majority and McConnell then became the GOP’s minority leader. “My, how my life changed,” McConnell told Kentucky Republicans here in western Kentucky.

By 2008, as the wars and imploding economy sank the public view of Republicans, Democrats had the rare chance to claim 60 seats, a filibuster-proof majority, and waged an aggressive attack on McConnell. It included Democratic ads that criticized McConnell’s role in negotiating a $700 billion bailout of Wall Street — the same legislation that Reid and Sen. Charles E. Schumer (N.Y.), chairman of the Democratic campaign arm, had negotiated with McConnell.

By 2010, with President Obama’s popularity sagging, Republicans went after Reid in their effort to reach the majority. GOP operatives parked in front of the Ritz-Carlton in Washington’s West End neighborhood, trying to get footage of Reid emerging from the condo that he owns and resides in — so the image could be used in attack ads back in Nevada portraying Reid as out of touch and elitist.

Reid had become such a lightning rod among Republicans that his no-name opponent raised $28 million. Six years earlier he won reelection so easily that, weeks before Election Day, he gave $1 million to Democratic committees benefiting other candidates.

“It was like I’d taken a bath, and I felt so clean,” Reid recounted in testimony this summer about a race that had no spending by outside interest groups. By 2010, Reid said, it was “back into the sewer.” He became so frustrated with the secretive outside money that he now supports a constitutional amendment requiring those groups to disclose all their donors.

Now it’s McConnell’s turn again.

‘Roughing up a leader’

McConnell traces part of the constant combat for leaders to the modern media, with cable news and the Internet speeding up the dissemination of information, with a focus on the leaders.

He likes to note that his opponent, Grimes, Kentucky’s 35-year-old secretary of state, is raising money based on the prospect of defeating someone of McConnell’s stature.

“I won’t ask for a show of hands of how many of you sent a check to Harry Reid’s opponent in 2010, but I bet it was a significant percentage of you,” he said as heads nodded throughout the school cafeteria.

Donald Ritchie, the Senate historian, compared this era to a 12-year run in the 1950s and early 1960s when the leadership posts were also held in less esteem. In 1950, Everett Dirksen (R) took out Senate Majority Leader Scott Lucas (D-Ill.), and two years later Barry Goldwater (R) defeated Lucas’s successor as majority leader, Sen. Ernest McFarland (D-Ariz.), making the leadership post so toxic that no one of prominence wanted it. That’s how Sen. Lyndon B. Johnson (Tex.) became Democratic leader in his first term.

The spread of super PACs has made it easier to find a few rich donors to support a steady stream of advertising.

“I think there’s so much outside money, outside groups can now decide they want to spend a lot of money roughing up a leader,” Thune said.

Of course, the largest super PAC for Senate Democrats is run by Reid’s former chief of staff, and the largest Republican super PAC is run by McConnell’s former chief of staff. Each super PAC places more strain on the personal relationship of the two leaders.

“I see your super PAC is up in Kentucky,” McConnell dryly said to Reid in the summer of 2013 when anti-McConnell ads began airing.

McConnell has made his distaste for Reid a hallmark of his 2014 campaign. At the Fancy Farm Picnic, the unofficial kickoff to campaign season in Kentucky, McConnell’s supporters wore masks of Reid’s face. Some carried two-sided signs with Grimes’s picture on one side and Reid’s on the other. Lines linking Reid to Grimes drew as much noisy displeasure as zingers about Obama.

“When she takes the first vote for Harry Reid, she kills any chance of resurrecting the Kentucky coal industry,” Sen. Rand Paul (R-Ky.) told the crowd.

If Grimes wins, she should expect to be virtually shunned by many Republicans. “It takes you a while to earn their friendship, their trust,” Thune said, recalling how some of Daschle’s friends would not talk to him.

Sen. Richard J. Durbin (D-Ill.), who drove through South Dakota knocking on doors for Daschle, said the loss burned him up.

“When you’re close to someone who loses and you think the race wasn’t totally on the square, then there’s a sense of grievance,” he said.

No one knows when this cycle will come to an end, but it may take quite some time as the leadership turns over and a new cast of senators is in charge.

“It is like organizational behavior, in large groups of people — they change slowly,” Rockefeller said. “It means the leadership has to change, the participants have to change. It’ll change. It can’t get worse.”