ALBUQUERQUE, N.M. (AP) — The federal agency that oversees the nation's nuclear weapons stockpile is expected this week to release a report on the best site option for the United States as it looks to ramp up production of the plutonium cores that trigger nuclear warheads.

At stake are hundreds of jobs and billions of dollars in federal funding that would be needed to either revamp existing buildings or construct new factories to support the work.

New Mexico's U.S. senators have been pushing to keep the work at Los Alamos National Laboratory — the once-secret city in northern New Mexico where the atomic bomb was developed decades ago as part of the Manhattan Project. The other option would be to move it to it to the U.S. Energy Department's Savannah River Site in South Carolina.

The mission of producing the cores has been based at Los Alamos for years but none have been produced since 2011 as the lab has been dogged by a string of safety lapses and concerns about a lack of accountability.

A team of engineering experts from within the National Nuclear Security Administration and outside professionals has been considering the two sites, which were identified as part of an earlier review that looked at the most efficient and cost effective means for making the plutonium cores.

The federal government has been tightlipped about the findings but a summary obtained last year by a watchdog group suggests that it would be most costly — possibly as much as $7.5 billion — to continue making plutonium cores at Los Alamos and that the lab might not be able to meet production goals until 2038.

The Energy Department wants to ramp up production to 80 plutonium cores a year by 2030.

U.S. Sens. Tom Udall and Martin Heinrich and Congressman Ben Ray Lujan, all New Mexico Democrats, have suggested the nuclear agency's evaluation process was flawed.

"It's hard to see how NNSA could justify uprooting and recreating the mission somewhere else will save time and money," they said in a statement issued after Los Alamos and Savannah River were identified as the options.

Greg Mello with the Los Alamos Study Group said in a recent interview with The Associated Press that Los Alamos' track record should give the Trump administration pause as it considers how to move forward.

Work at Los Alamos has been stalled by a series of mistakes, and criticism has mounted following mishandling of nuclear materials.

"In terms of safety, Los Alamos is the worst site in the complex for its arrogance and scofflaw attitude," Mello said.

In an internal memo, the lab argued last year that operations at its plutonium facility and its safety programs have undergone more than a dozen independent external reviews and that it was close to being fully operational after safety problems forced work to be suspended in 2013.

Internal government reports drafted earlier this year indicate serious and persistent safety issues still plague both Los Alamos and Savannah River, according to a recent report by the Center for Public Integrity.

Before the mission of making plutonium cores came to Los Alamos in the 1990s, there were concerns by lab officials and elected officials at the time about shifting from research and development to manufacturing. The critics included former U.S. Sen. Jeff Bingaman, D-New Mexico, who opposed expanding the lab's mission to include the production of parts for nuclear weapons.

It's only recently that the current generation of elected officials has been pushing for the work, Mello said.

"In a way that encapsulates New Mexico's whole problem — that we just haven't focused properly on what the people need and we're just slavishly devoted to these institutions that are basically colonial," he said.

If no decision is made by the National Nuclear Security Administration and senior officials don't accept the analysis by Friday, plutonium operations will remain at Los Alamos.