Sen. Jon Tester continues to run strong TV spots that add to his image as a "Montana Democrat," not a national Democrat.
Republicans and Democrats alike are nearly unanimous in praising Heitkamp's campaign and messaging. She is better liked than Republican Rep. Rick Berg, and she has so far been able to run about even with the Congressman even as GOP strategists try to tie her to the president. One Republican consultant claims that Heitkamp "is running the best campaign in America."
In the Bay State, Brown is a more personally appealing candidate than challenger Elizabeth Warren, and observers continue to give the Republican's campaign higher marks than the Democrat's. Warren clearly mishandled the issue of her ancestry.
In Indiana, early favorite Richard Mourdock, who clobbered veteran Sen. Dick Lugar for the GOP nomination, is widely seen as being far less agile and appealing as a candidate than Rep. Joe Donnelly (D). The Democrat won re-election to his House seat in 2010 by distancing himself early and repeatedly from his own party leaders in Washington, D.C., and Mourdock can be sour and off-key in his comments.
In Connecticut, businesswoman Linda McMahon, who lost the 2010 Senate race by a dozen points in a great Republican year (nationally, but not in the Nutmeg State), has remade herself and is running about even against Rep. Christopher Murphy (D). Unlike 2010 Democratic Senate nominee Richard Blumenthal, Murphy isn't known nearly as well statewide as McMahon, and the Congressman's prospects weren't helped by unflattering stories in state newspapers last week about financial missteps.
In the Treasure State, incumbent Sen. Jon Tester (D) is widely believed to be running a better campaign than Rep. Denny Rehberg (R). Tester continues to run strong TV spots that add to his image as a "Montana Democrat," not a national Democrat, while Rehberg's ads either rebut Tester's charges or link the Senator's voting record to Obama.
Of course, none of this answers the question of whether these strong candidates will, at the end of the day, win in difficult partisan territory and in a polarized presidential environment.
All six of the candidates will have to overcome a drag at the top of the ticket in their states, but ticket-splitting isn't unusual in this country.
In 2000, for example, Bush carried North Dakota by more than 27 points (61 percent to 33 percent) over Gore at the same time that Democratic Sen. Kent Conrad was winning re-election by more than 22 points (61 percent to 39 percent) over a weak Republican challenger.
Four years later, the state's other Democratic Senator, Byron Dorgan, was re-elected by more than 36 points (68 percent to 32 percent) in a noncompetitive race at the same time that Bush was being re-elected by 27 points (63 percent to 36 percent).
In the Hoosier State, in 2004, then-Sen. Evan Bayh won by 24 points (593,000 votes) at the same time that Bush was carrying the state by more than 20 points (510,000 votes).
Still, the country is more polarized than it was even just eight years ago, and Republicans didn't have formidable nominees in the 2000 North Dakota race or the 2004 North Dakota and Indiana races. This time, Brown, Heitkamp, Lingle, Tester, Donnelly and McMahon all face credible opponents with enough resources to win. And that makes the job of defeating them more difficult.
This year's battle, pitting quality candidates and campaigns against a state's partisan fundamentals and presidential preference, will go a long way to determining control of the Senate for the next two years.
Senate Minority Leader Mitch McConnell, R-Ky., carries a musket on stage as he speaks during the American Conservative Union's Conservative Political Action Conference (CPAC) at National Harbor, Md., on Thursday March 6, 2014.