It increasingly looks as if the Republicans will regain control of Congress this fall, with the GOP narrowly winning back a majority in the Senate and the House GOP either retaining or slightly building on its majority. But will the two top Republican leaders – House Speaker John Boehner and Senate Minority Leader Mitch McConnell -- be around to enjoy the spoils of victory?

Both Boehner of Ohio and McConnell of Kentucky are crafty and highly resilient veterans who would be difficult for their opponents to bring down even under the best of circumstances. Yet McConnell is facing arguably one of his toughest reelection campaigns this fall while Boehner appears headed for another tough internal challenge from far-right House conservatives for the speakership shortly after the mid-term election.

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While some political experts say it is far too soon to speculate on what the future holds for McConnell and Boehner, there are clearly some troubling signs on the horizon for the two leaders:

Mitch McConnell: While McConnell is expected to easily fend off a primary challenge from Tea Party favorite Matt Bevin, it will be a much rockier road for the 71-year-old leader in the general election against Alison Lundergan Grimes, the Democratic secretary of state. Lundergan Grimes, held an early 46 percent to 42 percent lead over McConnell in a Feb. 7 SurveyUSA poll conducted by the Courier-Journal and WHAS-TV in Louisville. A Rasmussen poll a few days earlier showed the two in a virtual deadlock.

Lundergan Grimes, 35, is the daughter of former Kentucky Democratic chairman and state representative Jerry Lundergan and the political protégé of former Democratic President Bill Clinton. Late last month, Clinton made his first 2014 campaign stop in Kentucky and helped Lundergan Grimes raise more than $600,000 at a downtown Louisville luncheon. While McConnell appears positioned to easily win the Republican primary, he'll be in the fight of his political life to win a sixth term as Kentucky's senior senator.

Lundergan Grimes’s lead is slender and could vanish as McConnell’s campaign turns up the heat. But McConnell has an added problem of surmounting an extraordinarily low approval rating among Kentucky voters. Only 32 percent approve of McConnell, which is lower than even President Obama’s 34 percent rating in the Blue Grass State.

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With women and young voters, McConnell trails Grimes badly, losing women 49 percent to 37 percent and Millennials by 43 percent to 34 percent. Among voters who identified themselves as politically "moderate," another key demographic, 55 percent said they had an unfavorable view of McConnell, compared with 15 percent for Grimes

McConnell campaign spokeswoman Allison Moore issued a statement saying that “We’re very comfortable about where the race stands and extremely confident that Sen. McConnell will earn the vote of Kentuckians this fall.”

John Boehner: Boehner was narrowly reelected speaker of the House in January 2013 with just six votes to spare after 12 conservative Republicans defected. The speaker’s standing with many of his most conservative members hasn’t improved in the subsequent year and a half. The National Journal reported last week that 40 to 50 frustrated House conservatives are scheming to infiltrate the GOP leadership next year – possibly by forcing Boehner to step aside immediately after the November midterm elections.

Boehner has survived previous insurrections with deft moves that occasionally won the plaudits of his conservative wing. But the biggest complaint now is that Boehner and his lieutenants are taking a “don’t rock the boat” approach to the election campaign, and are not promoting “big ideas.”

“The masterminds of this mutiny are trying to stay in the shadows for as long as possible to avoid putting a target on their backs,” according to the report. “But one Republican said the "nucleus" of the rebellion can be found inside the House Liberty Caucus, of which he and his comrades are members. This is not surprising, considering that some of the key players in that group—Justin Amash of Michigan, Raul Labrador of Idaho, and Thomas Massie of Kentucky—were among the 12 Republicans who refused to back Boehner's reelection in January 2013.

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