Bill Clinton stumps in Kentucky. Will he help topple Mitch McConnell?

Bill Clinton is riding into Kentucky to campaign for Alison Lundergan Grimes, the Democrat who is trying to topple Senate minority leader Mitch McConnell. Will the Big Dog be the deciding factor in one of America’s most closely watched Senate races?

It’s possible. Mr. Clinton’s favorable ratings rank him as close to the most popular politician in the nation. He remains well liked in the Bluegrass State, which he carried twice in presidential campaigns. And Clinton’s ties to Ms. Grimes and her family are longstanding. He and Hillary Rodham Clinton counseled her before she decided to run. Her campaign website prominently features a Clinton endorsement video.

For the Clintons, the Grimes race isn’t just business as usual. It’s personal.

“At 35, Grimes is just 15 months older than their daughter, Chelsea Clinton, and is practically the Clintons’ political offspring,” writes The Washington Post’s Philip Rucker. “A win in November would demonstrate the appeal of Clintonian centrism in Republican territory.”

Right now polls show Grimes, the current Kentucky secretary of State, tied or slightly ahead of Senator McConnell. In the RealClearPolitics rolling average of state surveys, the race is essentially a dead heat.

McConnell’s problem is that his personal favorable ratings are weak for a powerful incumbent. Kentucky voters see him as distant, perhaps a touch too Washingtonian. So with Clinton’s appearance, the race is nearing a tipping point, right?

Not so fast. McConnell has many strengths, among them lots of campaign cash and a demonstrated willingness to fight hard when threatened. You can bet that before the campaign is over, he’ll flood Kentucky airwaves with ads tying Grimes, not to Clinton, but to the chief executive she has no plans to appear with: President Obama.

Mr. Obama’s not popular in Kentucky, a red state where Mitt Romney took 60 percent of the vote in 2012.

Plus, right now it looks like McConnell won’t have to devote much time or energy to winning the Republican primary. He’s facing a challenge from tea party-backed businessman Matt Bevin, but so far that’s fizzled. Mr. Bevin has had to defend himself against charges that he once backed the federal government’s TARP bank bailout, a program loathed by many on the right. McConnell has hit Bevin repeatedly over the fact that the latter took state aid to rebuild a family bell factory after a fire. He’s “Bailout Bevin,” in McConnell ads.

Tea party groups from outside the state are moving to try to help McConnell’s foe. The Senate Conservatives Fund on Tuesday released a radio ad attacking McConnell’s vote to allow the debt ceiling bill to proceed, among other things.

“Mitch McConnell has betrayed Kentucky’s conservative values. That’s why it’s time to blow the whistle on Mitch McConnell and replace him with conservative Matt Bevin,” says the ad, to the sound of a whistle blowing.

But the group is putting only about $30,000 into air time for the ad, which is not a lot. And time is running out for Bevin. The primary is May 20, and polls show him anywhere from 26 to 42 points behind.

“Right now, Kentucky undoubtedly is the ‘most watched’ Senate race in the country. But does it deserve all that loving attention? Almost certainly not,” write University of Virginia political scientists Larry Sabato and Kyle Kondik in Politico. “The odds of McConnell, even with his weak approval ratings, losing either the primary or general election are not impressive.”