U.S. Rep. Ben Ray Luján’s announcement that he will run for the U.S. Senate had barely left his mouth before candidates started coming forward to take his place in the House of Representatives.

One campaign quickly begat many more, as District Attorney Marco Serna looked poised to enter the race as freshman state Rep. Joseph Sanchez, D-Alcalde, jumped into the contest along with Raton’s Mark McDonald.

State Public Regulation Commission member Valerie Espinoza, D-Santa Fe, said she was leaning toward running.

Luján has represented the 3rd Congressional District since 2009. Spanning Northern New Mexico, the district leans towards the Democrats. It has not sent a Republican to Congress in more than 20 years. But Republicans also could have a better shot at an open seat.

Sanchez was elected to the Legislature last year. In his first session, he passed legislation to develop the state’s agricultural workforce. But he also took a step that may dent his prospects with many Democratic primary voters, opposing a bill repealing an old law that makes it a crime to perform an abortion.

As a former general manager and CEO of Jemez Mountains Electric Cooperative, an engineer at Los Alamos National Laboratory and part of the well-known local band Los Blue Ventures, Sanchez may have a network of supporters in the North that could go a long way.

McDonald is a graduate of Des Moines High School and the University of New Mexico. He has worked as a paramedic and been involved in the Democratic Party in Colfax County.

He ran unsuccessfully for the state House last year. But he has been preparing to run for Congress if Luján were to step aside. McDonald said Monday that he would file to launch his campaign in the coming days.

Serna’s name has also quickly emerged among the list of potential candidates. Elected in 2016, he comes from a family with deep roots in Northern New Mexico politics. While a proven fundraiser, his biggest challenge might getting voters to look past his relative inexperience as a first-term district attorney.

Espinoza, a former Santa Fe County clerk, will wrap up her second term on the Public Regulation Commission in 2020. She represents a district that covers much of Luján’s constituency.

Espinoza said she is leaning towards running for Luján’s seat. And being from Santa Fe probably would be an advantage in the Democratic primary.

Michael Lucero, who won nearly 6 percent in the race for land commissioner last year despite running a fairly low-key campaign, also said he has made a preliminary decision to run for Congress in the 3rd District as a Libertarian.