WASHINGTON — President Barack Obama is serious about compromising on higher income-tax rates for the rich, but other Democrats have not offered specifics on what spending they are willing to cut, the co-chairmen of the National Commission on Fiscal Responsibility and Reform said Wednesday.

During a breakfast with reporters, Erskine Bowles and Alan Simpson said they are not optimistic that Congress and the White House would strike a deal to avoid going over the so-called fiscal cliff.

Bowles, a former chief of staff to President Bill Clinton, said he put the odds at just 1-in-3 that there would be a deal before year’s end.

“I believe that the probability is that we’re going over the fiscal cliff,” Bowles said, adding later, “I’m really worried.”

Bowles said he came away from a meeting Tuesday with the president and his economic team thinking that “these guys were serious” about finding a solution. He and Simpson criticized Congress as putting the nation’s economy at risk by showing little urgency in resolving the expiring tax cuts and scheduled deep reductions in government spending.

“If this was any business or any family, they’d have been working on it all year together,” he said.

Regarding Tuesday’s meeting with Obama, Bowles said the administration was willing to tax the rich less than stated publicly, and that the president wanted a significant deal.

Obama staged a campaign-style event Wednesday at the White House. He called on ordinary Americans to text, email, write or call their lawmakers to pressure them for a resolution of the tax and budget issues.

The president was flanked by “middle-class Americans” who he said would see their taxes go up by more than $2,000 a year if Congress can’t reach a deal.

If Obama is saying in private that he is ready to deal, in public he continues to push his campaign pledge to raise taxes on the top-earning 2 percent of Americans, and on Wednesday he repeated his campaign theme that both parties agree on extending expiring the tax cuts for everyone else.

“Let’s begin our work with where we agree,” the president said. “If we get that done, a lot of the other stuff is going to be a lot easier.”

Treasury Secretary Timothy Geithner is scheduled to meet today with congressional leaders of both parties, the White House said.

Bowles criticized his fellow Democrats for focusing on taxation while refusing to spell out where they are willing to reduce spending and by how much.

“We need to talk more about the spending side of the equation,” he said, adding that Obama’s projected spending cuts in his proposed 2013 budget are not sufficient.

House Speaker John Boehner, R-Ohio, picked up this theme in his own news conference Wednesday. Republicans, he said, are willing to agree to more tax revenues, but “it’s time for the president and Democrats to get serious about the spending problem that our country has.”

A folksy Republican former senator from Wyoming, Simpson rapped GOP lawmakers as intransigent, likening them to a rigid fireplace poker but “without the occasional warmth.”