A far-reaching plan to cut U.S. deficits and slow the growth of long-term debt gained crucial support from two key Republican senators on Thursday but remained short of votes needed to trigger congressional action.

Republican Senators Tom Coburn and Mike Crapo announced plans to back the recommendations of a commission set up by President Barack Obama to address the federal government's widening budget deficit.

Their backing brought to nine the number of panel members who have declared they will vote yes for the plan, which proposes a major tax overhaul and significant spending cuts to eventually balance the U.S. budget.

The panel's co-chairmen, Democrat Erskine Bowles and Republican Alan Simpson, unveiled the plan on Wednesday and set a vote by commission members for Friday.

"Our debt crisis is a threat to not just our way of life, but our national survival," the two senators said in a joint statement. They held a news conference to announce their decision to back the plan. "This plan will not just avert a disaster but help drive the kind of economic recovery we need to create jobs and spur growth," they argued.

However, they said the plan does not go far enough in addressing rising healthcare costs. They argued that 80 percent of the debt problem comes from the government-run Medicare health program for the elderly.

They said that all Americans should be prepared to sacrifice in the effort to tackle the $1.3 trillion deficit and $13.8 trillion national debt.

Despite their support, it appears unlikely the plan will win the 14 votes needed on the 18-member panel to prompt a quick congressional vote.

Democratic Representative Jan Schakowsky, a commission member, said she would vote against the plan.

Other members have not declared their positions, but Senate Finance Committee Chairman Max Baucus, who also sits on the commission, is likely to oppose it, as are some of the House Republican members.

Meanwhile, commission member Andy Stern submitted his own deficit reduction plan on Thursday. That plan calls for spending cuts but seeks more immediate spending to help revive the lackluster economy and create jobs.

Stern told reporters on Wednesday he was undecided about whether to support the commission plan.