WASHINGTON - With a year-end deadline approaching, negotiations to avoid an economy-rattling fiscal cliff appeared at a standstill Monday. Republicans pressed President Obama to name specific spending cuts he would support, while the White House insisted the GOP agree explicitly to raise tax rates on upper incomes.

At a campaign-style event in Michigan, Obama warned his listeners that their taxes would rise Jan. 1 without action by the Congress. "That's a hit you can't afford to take," he declared.

He spoke one day after meeting privately at the White House with House Speaker John Boehner, whose office expressed frustration with the talks to date.

"We continue to wait for the president to identify the spending cuts he's willing to make as part of the 'balanced' approach he promised the American people," said a written statement from the Ohio Republican's office.

Many Republicans agree that Obama and the Democrats hold most of the political leverage, given the president's reelection more than a month ago after a campaign in which he said the wealthy should pay more in taxes. Obama spoke by phone Monday with Senate Majority Leader Harry Reid (D., Nev.) while traveling aboard Air Force One, according to a Democratic aide. The aide was not authorized to speak publicly about the private conversation and thus spoke on condition of anonymity.

If anything, the president has toughened his demands in recent days, insisting not only that tax rates must rise, but also that Congress give him and future presidents the authority to raise the government's borrowing limit without prior approval by lawmakers.

Boehner has said repeatedly he opposed Obama's plan to raise tax rates for anyone, adding that he prefers to raise revenue by closing loopholes. Yet he has not yet ruled out giving the president his way, and some Republicans have said they are prepared to do so - encouraging Democrats to say they anticipate the speaker will eventually yield on the point.