SANTA FE, N.M. >> New Mexico Senator Tom Udall announced today he will not seek re-election in 2020 in a move that opens up a secure Democratic seat to competition.

The second-term senator and former congressman said in a statement he is confident he could run a strong campaign but preferred to look for new ways to serve the public, without specifying how.

The decision marks an end to a 20-year political career on Capitol Hill for Udall, who first was elected to Congress in 1998.

Udall’s father was Stewart Udall, who served as Interior Secretary in the 1960s and helped write far-reaching conservation legislation. And his uncle was Morris “Mo” Udall, a longtime Arizona congressman and a prominent Democratic 1976 presidential contender.

Since 2017, Udall has helped organize resistance in Congress to attempts by the administration of President Donald Trump to roll back development restrictions on public lands, while defending the regulation of heat-trapping gasses linked to climate change.

The 70-year-old Senator from Santa Fe said he’ll dedicate the final two years of his term to fighting climate change, protecting public lands and to trying “to stop the president’s assault on our Democracy and our communities.”

“The worst thing anyone in public office can do is believe the office belongs to them,” Udall said in a videotaped message . “There will be more chapters in my public service to do what needs to be done.”

In 2008, Udall readily defeated then-U.S. Rep. Steve Pearce to take Democratic control of a Senate seat held for 36 years by Pete Domenici, who retired when diagnosed with a degenerative brain disease and died in 2017.

New Mexico’s junior senator, Democrat Martin Heinrich, last year won re-election, easily defeating former Libertarian New Mexico Gov. Gary Johnson and Republican political newcomer Mick Rich.

Democrats consolidated control of New Mexico’s delegation to Washington in November elections, when U.S. Rep. Xochitl Torres Small last year flipped a district in the south of the state that was long dominated by the GOP.

Democratic colleagues in Washington and serving in statewide office rushed to praise Udall for his record on environmental conservation and the protection of public lands — a Udall family trademark — and as an advocate for Native American communities that span New Mexico.

“New Mexico will lose a powerful advocate,” said Sen. Dianne Feinstein of California, praising Udall’s work on renewable energy and tribal land issues.

Udall used the announcement of his approaching retirement to sound an alarm about the threat of climate change, the influence of anonymous spending on politics and the potential for new armed conflicts without the authorization of Congress.

Born in Tucson, Arizona, Udall hails from a ranching family that once drove cattle across territorial New Mexico.

He studied law and got off to a shaky start in politics, losing two initial bids for Congress. He served two terms as state attorney general before defeating an incumbent Republican Congressman in 1998.

Defining votes in Congress and Senate include opposition in 2002 to war in Iraq and his rejection of federal bailout packages designed to save the nation’s economy after the Great Recession.

His work on behalf of Native American tribal communities across New Mexico included recent efforts at stricter laws against the sale of Indian cultural artifacts and fraudulent indigenous art. He is seeking a permanent land buffer to keep oil and gas drilling away from Chaco Culture National Historical Park and other sites held sacred by Native American tribes.

It was initially unclear whether Torres Small or two other members of New Mexico’s U.S. House delegation — also Democrats — might compete for Udall’s vacant seat.

Rep. Ben Ray Lujan, 46, is a member of House Democratic leadership, and first-term Congresswomen Debra Haaland of Albuquerque fended off a crowded field of Democrats in last year’s primary.

A Lujan spokeswoman declined to comment on whether he would run for Senate. Haaland and Torres Small aides did not immediately return messages left for them.

New Mexico Republicans are scarce in prominent public offices, having been driven out of every stateside elected office in the 2018 elections. Democrats serve as mayor in three of the state’s four largest cities — Albuquerque, Santa Fe and Las Cruces.

Udall was spending the day with family in Santa Fe after making the announcement.