Rep. Heather Wilson intends to seek the Senate seat being vacated in New Mexico by fellow Republican Pete Domenici, the Associated Press has learned.

Wilson made the decision Thursday after meeting with her family and notified her staff Friday morning. She was calling supporters around New Mexico to tell them of her decision, according to a senior adviser to Wilson who spoke on condition of anonymity so as not to pre-empt a formal announcement expected later Friday.

Wilson is the first major candidate to declare her candidacy for the seat, which Domenici has held since 1973. Earlier Friday, Democratic Rep. Tom Udall announced that he would not run for the seat.

On Thursday, Domenici announced that he was retiring in January 2009, at the end of his sixth term. He said he had been diagnosed with an incurable brain disease that might prevent him from fulfilling a seventh term in office.

Wilson, 46, an Air Force Academy graduate and Rhodes Scholar, has represented the Albuquerque-area 1st Congressional District since winning a special election in 1998. Albuquerque is the state's largest city and the metropolitan area is a critical battleground for candidates in statewide races.

Known as a tough campaigner, she has survived several hard-hitting, well-funded challenges by Democrats. She won re-election last year by 862 votes.

Wilson was drafted to run for the congressional seat by Domenici when the GOP incumbent, Steve Schiff, died of cancer. Her election made her the first woman from New Mexico to serve in Congress since Democrat Georgia Lusk in the 1940s.

In Congress, Wilson has broken party ranks when necessary to keep in line with the moderate views of her swing district. She voted in 2002 to authorize President Bush to use military force in Iraq, but has since criticized the president's handling of the conflict and opposed Bush's increase in troops in the war zone.

Among other potential GOP contenders for Domenici's Senate seat are Republican Rep. Steve Pearce. Lt. Gov. Diane Denish, Albuquerque Mayor Martin Chavez and former Attorney General Patricia Madrid are other Democrats eyeing the race.

Democratic Gov. Bill Richardson said Thursday that he remains focused on his presidential bid.

On Capitol Hill, Domenici was known as a deficit hawk for his budget-balancing work in the 1980s and '90s as chairman or the senior GOP member of the Senate Budget Committee. He also watched closely over New Mexico's interests and used a seat on the powerful Appropriations Committee to steer money to federal installations in the state such as Los Alamos and Sandia national laboratories.