Democrats Alison Lundergan Grimes and Michelle Nunn have a lot in common. That's especially true when it comes to Obamacare.

Democratic candidate for U.S. Senate, Michelle Nunn celebrates her primary win with supporters at an election-night watch party Tuesday, May 20, 2014 in Atlanta. (AP Photos/Akili-Casundria Ramsess)

Neither U.S. Senate candidate will say whether she would have voted for the federal health-care law in the U.S. Senate. Why? The political realities of their races are such that they pretty much have no other choice.

Fresh off her primary victory last Tuesday in Kentucky, Grimes twice refused on Wednesday to say whether she would have voted for the law, according to the Associated Press. When asked by The Fix for clarity on her position on Thursday, Grimes's campaign forwarded a statement from her that sidestepped the question once again.

"If I had been in the Senate, it would have been a different law," Grimes said in the statement. "As Kentucky's next Senator, I will vote to fix it -- which is more than Mitch McConnell would do. I've said all along that the law isn't perfect and there are parts that need to be fixed."

When asked whether she would have voted for the law by MSNBC multiple times last week, Nunn said, "I think it's impossible to look back retrospectively and say, 'well what would you have done while you were there?'" Nunn suggested tweaks to the law like adding a "more affordable tier" of insurance and adding a tax credit for small businesses.

Here's the reality: As much criticism as Grimes and Nunn are receiving for not answering the question directly, they'd both be in much worse positions politically if they did.

Saying, "Yeah, sure, I would have voted for it" would be instant fodder for a Republican attack ad that practically writes itself. Both candidates are running in red states where they simply can't afford to be portrayed as full-scale champions of an unpopular law signed by an unpopular president.

At the same time, saying, "Nah, I would have voted against it" would open Grimes and Nunn up to charges of hypocrisy, since they both say they reject repealing the entire law. What's more, Nunn and Grimes can't afford to alienate Democratic base voters who like the law and don't want it to go away.

Grimes and Nunn represent Democrats' two best chances to pick up seats in the battle for the Senate this year. As such, they are going to have walk fine lines on many issues. Health care is clearly one.