There's sort of a rule in the gamesmanship of politics: if you are the frontrunner, you don't want to accept debate challenges from your lesser-known opponents.

The usual reason for refusing to debate is the presumption that all the joint appearances do is allow your opponents allow your opponents some exposure on an equal footing that they otherwise wouldn't get. That presumably is the logic that state Rep. Rick Noriega, DHouston, is following in his campaign for the Democratic nomination for the U.S. Senate, by spurning challenger Ray McMurrey's call for a face-off.

"I don't anticipate that happening," said Sue Schechter, manager of Noriega's campaign.

Noriega must thinking that having already raised $1 million, he can afford TV ads when they can't. But it does look a little odd when a lieutenant in the Texas Army National Guard, who served 14 months in Afghanistan training police, refuses a political debate.

And, presuming a debate would be on neutral turf, like at a public television station Noriega is passing up an opportunity to put the Senate race on the public's radar screen. He might take some punches, but it could give him free media exposure for himself and the Senate race, but show he can handle himself against opponents.

He'll certainly need that if he's the Democratic nominee against Republican incumbent U.S. Sen. John Cornyn.

Noriega, now in his fifth term in the Texas House of Representatives, is no stranger to debate. He's bright and articulate, and has a sense of humor he hasn't demonstrated much on the campaign trail. He should consider that exposure might hurt rather than help his opponents.

The other three candidates are:

• McMurrey, 42, a Corpus Christi school teacher (who says on his Web site "Donate $5 and receive a free bumper sticker");

• Private security guard Rhett R. Smith, 57, of San Antonio (who ran for the Republican gubernatorial nomination in 2006; he finished third, with 4.6 percent);

• Perennial Democratic spoiler candidate Gene Kelly - the retired Air Force lawyer, not the dead dancer - of San Antonio, who is 81. (Democratic party operatives wish Kelly would move to Oklahoma.)

Noriega is fortunate to be the only Hispanic against three Anglos. Another Hispanic might dilute his vote.

It's possible the three Anglos may draw enough votes that Noriega doesn't win a majority, and is forced into a runoff. But he may be able to escape that, with the help of Democratic House buddies in their home districts, plus TV ads.

Even if there is a runoff, he can take solace from the fact that often around half the votes in Democratic runoffs are cast in heavily Hispanic districts, because many contests in those districts are decided in the Democratic primary, not the general election.

Presuming Noriega makes it to the general election, he'll have to raise considerably more money to go against Cornyn, who already has $6 million in the bank and will probably raise plenty more.

But if Noriega is the nominee, and the shift continues back in a Democratic direction, Noriega may attract enough money from national sources, such as the Democratic Senatorial Campaign Committee, to have a decent advertising presence.

Meanwhile, during public appearances, Noriega opponents like McMurrey might resort to using an empty chair, or a life-sized cardboard cutout of Noriega, to underline Noriega's refusal to debate.

While it's understandable that Noriega would duck the debate, it could do him more harm than good. It certainly will give Cornyn, who has indicated he's willing to debate primary opponent Larry Kilgore, an excuse to refuse to debate Noriega in the fall.

And so on. . . .

Cornyn opponent Kilgore also ran for the GOP nomination for governor in 2006. He finished a distant second to Gov. Rick Perry, with 7.6 percent.

Kilgore, of Mansfield, wants to run the state according to the Bible, and also wants Texas to secede from the United States.

Contact McNeely at dmcneely@austin. rr.com or (512) 458-2963.