Roger Clemens will raise the right arm tomorrow that made him rich and famous, swear he's going to tell the truth, and then try to convince a group of politicians more interested in their re-election prospects than they are about syringes in the clubhouse that he didn't win seven Cy Young awards by cheating.

Brian McNamee will raise his much less well-known arm to swear on the same stack of Bibles that some of those syringes filled with steroids and human growth hormone ended up in Clemens' rear end and he's got a crushed beer can full of empties to prove it.

By now, we know both story lines all too well. Attorneys for both men have long since drawn a line in the sand and dared the other to cross.

Now they get the chance, before a Congressional committee on national television with a lot more than just their reputations at stake. They'll testify under the very real threat of perjury, with the very real chance that one of them could someday be going to prison for what he says.

One of them is lying. That much we know for sure.

The only question is whether the 41 members of the House Committee on Oversight and Government Reform have the guts to find out which one it is.

My guess is they don't, partly because there's not a lot to gain by trashing a sports hero in an election year. A few members of the committee who met with Clemens last week have already indicated they think he's a great guy and are inclined to believe him unless there's a video on YouTube showing McNamee injecting him with human growth hormone.

Kind of hard to ask tough questions if you're asking for autographs first.

Committee members likely breathed easier when the witness list was pared last night and Andy Pettitte, Chuck Knoblauch and steroids dealer Kirk Radomski were spared from giving public testimony. In Pettitte's case it was reportedly because he didn't want to say bad things about his good friend in the glare of the television lights, and who can blame him.

If true, that's bad news for Clemens, because Pettitte has already answered questions — and lots of them — under oath to congressional investigators and those answers could be read aloud at the hearing. If Pettitte confirms he had conversations with Clemens about HGH and gives some of the details of those conversations, it could be a long day for the soon-to-be-retired pitcher, even with star-struck congressmen asking the questions.

Then again, judging from the way Mark McGwire was so gingerly treated when he told many of the same politicians that he didn't want to talk about the past there won't be many follow-up questions asked of Clemens once he issues his indignant denials. Not one committee member ever demanded that McGwire answer questions instead of dancing around the question of whether he used steroids.

Don't be surprised if McNamee's character becomes the central issue instead of Clemens' alleged steroid use. No one likes a drug pusher, even if the only drugs McNamee was pushing were to help his clients gain a few extra miles on their fastball or find the gap more often with their line drives.

It's not only easy but politically correct to go after McNamee, despite various online surveys that show the public by a 2-1 margin believes Clemens is the one doing the lying. No one is going to lose votes grilling the personal trainer on why he gave players illegal steroids, or why he has gotten immunity from prosecution for telling his story.

Assuming that both McNamee and Clemens stick to their scripts, it then becomes a question of how hard the politicians want to push and for how long. Are they really interested in finding out the truth, or is this just a good excuse to get on television and do some pontificating and preaching for the folks back home?

Will they ask enough tough questions so that Clemens and McNamee are forced squarely on the record, knowing that they can be prosecuted for perjury if enough other evidence exists to show they are lying?

Again, my guess is no. Not only do members of Congress tend to tread carefully in such matters, but the unwieldy size of the committee works against any one member opening up significant lines of effective questioning.

Expect some drama when Clemens and his accuser are in the same room together. Expect emotions to run high and some raw feelings on both sides.

But don't expect this to settle anything. It's not a court of law, not even a court of public opinion.

Those who believe Clemens will come away still believing him. Those who believe McNamee will do the same.

One hearing isn't likely to change that.