Updated 11:44 a.m. | Rep. Ben Ray Luján plans to run for the Senate in New Mexico and is set to officially announce his candidacy Monday, according to two sources familiar with the Democrat’s decision.

The seat opened after Democratic incumbent Tom Udall announced Monday he would not seek re-election.

Luján, the assistant speaker and former chairman of the Democratic Congressional Campaign Committee, will be a formidable candidate. But he also isn’t likely to have the field to himself.

Rep. Deb Haaland and New Mexico Secretary of State Maggie Toulouse Oliver have been mentioned as potential candidates.

Toulouse Oliver tweeted Thursday that she was “seriously considering” a Senate run and would announce her decision “in the days ahead.”

State Attorney General Hector Balderas in a radio interview Thursday took himself out of contention , saying that he wanted to remain in his current position and stay with his family in New Mexico. 

“We have a great candidate in the wings,” Balderas told Coyote 102.5, but he did not specify who he was referring to. “We may have some other great candidates in the wings. But I can assure you that we will all together elect a great U.S. senator from New Mexico.”

Balderas later included Luján’s Twitter handle in a tweet announcing his decision.

I’m staying home! Thank you @SenatorTomUdall and Jill for your many years of service and sacrifice. I look forward to continue serving New Mexico’s families as your Attorney General. @peopleforben #nmpol pic.twitter.com/QcIKlCaIAN

— Hector Balderas (@HectorBalderas) March 28, 2019

Democrats start with the early advantage in the New Mexico Senate race. Inside Elections rates it Solid Democratic.

Bridget Bowman contributed to this report.