SEATTLE — Republican Senate candidate Dino Rossi is accusing Democratic Sen. Patty Murray of being soft on the Yucca Mountain repository proposed for the nation's high-level radioactive waste, and she's firing back by accusing him of wanting to pull the plug on Hanford environmental cleanup money.

The war of campaign news releases heated up Wednesday, just as Murray is expected to introduce a Senate amendment today that would provide money to continue work to license the Nevada site picked for the nation's high-level nuclear waste repository.

Rossi is claiming credit for Murray's amendment.

Murray has "finally responded" to Rossi's request that she take action to restore funding for Yucca Mountain, said his campaign spokeswoman, Jennifer Morris, in a news release.

It's the fourth news release the Rossi campaign has put out since June 30 questioning Murray's commitment to Yucca Mountain, which was the expected destination for Hanford's high-level radioactive waste.

President Obama has moved to shut down the repository and that's seen as a key win for Democrat Harry Reid, Senate majority leader, as he campaigns for re-election in Nevada. As the fourth-ranking member of Democratic Senate leadership, Murray works closely with Reid.

But she's been fighting for Yucca Mountain since 2002, her campaign said in response to Rossi's criticism. She was one of just five Democrats to support designating Yucca Mountain as the site for the national repository then, her campaign said.

When the Obama administration released a proposed budget for 2011 in February that withdrew money for the repository, Murray called it "irresponsible," in a Herald article.

The amendment she'll propose today is the first time members of the Appropriations Committee will have had an opportunity to weigh in on the Yucca Mountain funding issue with proposed legislation, her campaign said.

But Rossi's camp said she could have taken a stronger stand for Yucca Mountain by introducing a resolution in the Senate in support of it. Resolutions give lawmakers a way to present their opinions but typically do not carry the force of law that a bill does.

"Sen. Murray has been unwavering in her support of Hanford cleanup and Yucca Mountain for more than 10 years," said Gary Petersen, Tri-City Development Council vice president of Hanford programs. "I don't know what more she could be doing than what she is doing."

Murray and Rep. Doc Hastings, R-Wash., worked together in early July to get 91 members of Congress from 35 states to sign a letter to Energy Secretary Steven Chu urging the Department of Energy to immediately stop work on dismantling the Yucca Mountain repository.

Rossi may be trying to paint Yucca Mountain as a partisan issue for Murray, but more Republican senators than Democrats signed on, Petersen said.

"It shows her reach across the aisle," he said.

Murray is countering Rossi's attack by pointing out that he's calling for all unspent federal economic stimulus money to be returned and used for deficit reduction.

Murray has secured $1.96 billion in economic stimulus money for Hanford, which so far has created 2,900 full-time jobs, according to Department of Energy figures.

By the most recent DOE figures available, about $1.3 billion has yet to be spent.

"Dino Rossi needs to explain to the people of the Tri-Cities why he would take those jobs away," said Murray's campaign communications director, Julie Edwards, in a news release.

The Hanford Atomic Metal Trades Council, an umbrella labor organization of 15 local unions whose members work at Hanford, also jumped into the fray in Murray's support Wednesday.

"There has never been any doubt as to where Sen. Murray stands when it comes to cleaning up Hanford and opening a national repository for nuclear waste at Yucca Mountain," said Fred Rumsey, chairman of HAMTC's political committee.

Rossi purposely has misstated the facts, insulting Hanford workers and the Tri-City community, he said. Hanford cleanup and the need for Yucca Mountain have never been partisan issues here, Rumsey said.

"Instead of making blatantly false accusations just to get elected, maybe Mr. Rossi could follow Sen. Murray's lead in working across the aisle with members from both parties," he said.

Rossi's camp did concede Murray questioned the energy secretary at a congressional hearing in March on DOE's stand on Yucca Mountain. She repeatedly pressed Chu on whether he could show any scientific basis for terminating the repository.

But "statements and strongly worded letters" are not enough, Rossi's news releases said.

"Patty Murray needs to stop talking about standing up for Washington and actually stand up to her fellow leaders who are derailing this project, which is important to our state," Rossi said.

Murray will be introducing her amendment for a vote by the Senate Appropriations Committee today.

The committee also will consider the Department of Energy budget, which Murray announced this week would include $50 million more for Hanford work, including cleaning up contaminated ground water, than the Obama administration had requested.