ALBUQUERQUE — Taking the stage to the music of Tom Petty's "I Won't Back Down," U.S. Rep. Tom Udall on Thursday formally kicked off his campaign for U.S. Senate.

The Santa Fe Democrat stressed his opposition to the Bush administration, his record of voting against the Iraq War and the federal Patriot Act, and his support of environmental legislation.

Speaking to a ballroom filled with supporters at the National Hispanic Cultural Center, Udall never directly mentioned by name other candidates for the Senate seat being vacated by retiring Republican U.S. Sen. Pete Domenici, a Republican.

The five-term Congressman enters the race as a front-runner. Polls made public so far show him ahead of other major candidates. Plus he already has at least $800,000 in campaign funds. His main Democratic primary opponent, Albuquerque Mayor Martin Chávez, said this week that he's collected about $300,000 so far.

Asked after his speech about possible debates with his primary opponents, Udall wouldn't commit. "We'll see," he said, saying his Congressional schedule might conflict with debates.

In a message to his fellow candidates, Udall said, "Let us keep it positive and purposeful and focus on what really matters to the American people."

In addition to Chávez, Udall in the Democratic primary in June will face Leland Lehrman, who edits an alternative newspaper in Santa Fe. Democrat Jim Hannan, finance director of a Santa Fe housing trust, dropped out of the race Thursday and endorsed Udall.

On the Republican side, New Mexico's other two members of the U.S. House of Representatives, Heather Wilson of Albuquerque and Steve Pearce of Hobbs are running for the Senate nomination.

Udall, who served as New Mexico attorney general for eight years, said, "I know it's possible to be tough on crime without abandoning the Constitution. And I know it's possible to be tough on terrorists without alienating the rest of the world."

Udall was introduced by Maj. Gen. Melvyn Montaño, former adjutant general of the New Mexico National Guard, whose biggest applause line came when he said Udall "voted against allowing the president to get us into the tragic and misguided war in Iraq."

Since Democrats regained congressional majorities in the 2006 election, Udall said, the U.S. House has passed several good bills, including measures establishing timetables for troop withdrawals from Iraq, but "the Senate is where all this legislation has gone to die."

Chávez in recent days has blasted Udall for his vote for a bill reducing funding for national laboratories in New Mexico. Republicans also have criticized Udall for the vote. Some state GOP officials showed up at Udall's announcement Thursday to distribute literature attacking him on the lab vote and other issues.

But Udall didn't use his announcement speech to fire back at critics.

After his speech, he spoke to reporters about the lab vote — which gained new attention in recent days after Los Alamos National Laboratories announced the possibility of 750 job cuts.

"The first thing you have to understand is the nuclear weapons complex is going to shrink," he said. "We know that is going to happen. The Bush-Cheney administration is pushing that hard."

Udall said he spoke against the funding cuts in the House Appropriations Committee, offering an amendment to add $200 million for the nuclear-weapons lab at Los Alamos to take its research in new directions — specifically in the areas of alternative energy, climate change and homeland security. "My vote was about the jobs of the future," he said. "That's what people in New Mexico want for the labs."

Chávez's campaign manager, Mark Fleisher, responded: "That's the lamest excuse I've ever heard for negatively affecting thousands of New Mexico families." Fleisher said the decrease in lab funding would have a ripple effect on other businesses around the state.

Among those who stood on the stage with Udall were Santa Fe Mayor David Coss; state Sen. Dede Feldman, D-Albuquerque; state Reps. Tomas Garcia, D-Ocate, Al Park, D-Albuquerque, and Elias Barela, D-Belen; and former state Senate President Pro-tem Richard Romero, D-Albuquerque.

Also on the stage with Udall were family members including his father, former U.S. Interior Secretary Stewart Udall; wife, Jill Cooper; stepdaughter, Amanda Cooper, who is a deputy campaign manager for Gov. Bill Richardson's presidential campaign, and her husband Jim Noel, executive director of the state Judicial Standards Commission.

Also attending Udall's event were former state labor secretary and one-time television news reporter Conroy Chino and former state Health Secretary Michelle Lujan-Grisham, who is running for the 1st Congressional District seat in Albuquerque.

The event kicked off a three-day tour of nine New Mexico cities by Udall, which is scheduled to end in Santa Fe with a speech at Eldorado Hotel at 4 p.m. Saturday.

The Associated Press contributed to this report.

Contact Steve Terrell at 986-3037 or sterrell@sfnewmexican.com.