When Congressman Jim Matheson RSVPs "no" to his party's presidential bash year after year, he's thinking of conservative Utah voters. This year, he's avoiding the Democratic National Convention in Denver.

He says his calendar is full. He's too busy. His son is starting the fourth grade. The same explanations he's offered before - with a few tweaks.

"It's kind of an important week to be around," he says.

All these excuses seem so unnecessary.

I'll give Matheson the benefit of the doubt for 2000, when he was a new pol, running for a seat held by a Republican. Two years later, he had a brand new, statewide, Republican-leaning district to woo in a little over two months - courtesy of state lawmakers. And in 2004, Dick Cheney jetted into town to raise funds for Matheson's resurgent challenger, John Swallow. I get it. I do.

But this year, I'm a little perplexed. I understand the politics, but not the principle. This year, when history will be made, when Democrats will pick the first African-American candidate for a major party - ever - Matheson is not going to make an exception. This year, two years after he trounced former legislator LaVar Christensen by 20 points, Matheson is running the same campaign he ran eight years ago.

Spokeswoman Alyson Heyrend says her boss is consistent - a post-partisan workhorse, a conservative Blue Dog Democrat, concerned about every voter in a district that stretches from Salt Lake City's Avenues to St. George.

"His reasons for doing what he does in August have never changed," says Heyrend.

But after eight years in office, nearly a decade of building name recognition, voter loyalty and a fundraising juggernaut, you'd think the Democratic incumbent - even in Utah - could go to his party's convention.

In 2000, in that Salt Lake County district, Matheson got 27 percent of Republicans to vote for him, according to the Utah Colleges Exit Poll. Two years later, that number dipped to 20 percent - a low point. In 2004, 34 percent of Republican voters in the district crossed over for Matheson. Two years ago, even clinging to President Bush's coattails, Christensen was unable to shift the electorate much; 32 percent of GOP voters picked Matheson.

Matheson is not the only one avoiding the partisan pomp and circumstance. NBC reports that eight Republican senators will not attend the GOP convention in Minneapolis next week.

There is little risk for Matheson in bailing on his party's party. He still gets nearly 100 percent of Democratic votes and more than two-thirds of independents'. Although he cannot be replaced as a superdelegate, state Democratic officials are hesitant to criticize. Matheson is the top of the ticket for Utah's minority party. Anything he has to do to get re-elected.

"He is never safe," says Quin Monson, assistant director of Brigham Young University's Center for the Study of Elections and Democracy. Monson says Matheson's share of Republican votes seems to have peaked. Any change in strategy - any footage of Matheson sitting on his hands during Obama's speech, or worse, clapping - could leave an opening for a conservative challenger.

"He's right to be cautious," adds Monson.

Obviously, something Jim Matheson is doing works year after year. Against all odds, conventional wisdom, the best gerrymandering in the country, a Democrat keeps winning in Utah's Second Congressional District.

So go ahead, Congressman, stay home.

But can I have your tickets?

walsh@sltrib.com