The Senate's top Democrat on budgetary issues said that colleagues should be willing to "sacrifice" their political careers in order to get the U.S. on a better fiscal path.

Sen. Kent Conrad (D-N.D.), the chairman of the Senate Budget Committee, said that bringing down deficits and debt would require tough choices like the ones proposed on Wednesday by the leaders of President Obama's fiscal commission, recommendations that have already been met with a chilly reception.

"There is no way of doing it that's not controversial or difficult," Conrad said on ABC's "Good Morning America" of the panel's recommendations. "If some of us have to sacrifice a political career to get this country back on track, then so be it."

The Democratic and Republican co-chairmen of the fiscal commission, of which Conrad is a member, released an initial report on Wednesday calling for tax reforms, spending cuts and changes to entitlement programs like Social Security. Their recommendations on Social Security — raising the retirement age to 69, curbing the growth rate in benefits and limiting payouts to wealthy Americans — have garnered loud criticism from liberals, including outgoing House Speaker Nancy Pelosi (D-Calif.).

Conrad challenged those liberal critics of the plan to make counterproposals if they're so dissatisfied with the co-chairmen's report, which doesn't represent the final recommendations of the commission.

"I would agree with what the president said. Instead of shooting this down, propose an alternative — but one that does as good of a job as this one does at getting us back on a sound fiscal choice," he said. 

The president spoke of the political difficulties surrounding the commission, and said that those difficulties were precisely the reason he established the commission.

"I set up this commission precisely because I’m prepared to make some tough decisions," Obama said of his commission's initial report during a press conference in Seoul, South Korea. "The only way to make those tough choices historically has been if both parties are willing to move forward together."

The early chafing at those recommendations reflects the political difficulties that go hand in hand with the fiscal commission's work. Conservatives have criticized some of the reforms in the plan, too, particularly the tax reforms that would end certain tax breaks and allow the payroll tax to collect on higher income, though the chairmen's report called for cuts to income tax rates.

"Look, people can say we just want to keep what is," Conrad responded on Thursday. "But what is is not affordable, not sustainable."