WASHINGTON Dec 12 (Reuters) - U.S. House of Representatives Speaker John Boehner said on Wednesday he still has "serious differences" with President Barack Obama over how to resolve the year-end "fiscal cliff" as top Republicans vowed to stay in Washington until just before - and after - Christmas to reach a deal.
"I was born with a glass half full. I remain the most optimistic person in this town. But we've got some serious differences," Boehner told reporters at a news conference.
In recent days, Obama and Boehner have traded new proposals for replacing $600 billion in harsh tax hikes and spending cuts set to begin on Jan. 1 - the "fiscal cliff." But neither side seemed interested in the swapped plans.
The apparent lack of progress led Boehner to advise his rank-and-file Republicans, during a meeting early on Wednesday, to plan to stay in Washington through Christmas and possibly New Year's.
"Keep your Christmas decorations up and make no plans" to leave Washington, was Boehner's advice, Republican Representative John Shimkus of Illinois told reporters.
Much of the dispute between Republicans and Democrats centers on the amount of new revenues that would have to be raised to help shrink annual budget deficits that have been hovering around $1 trillion.
Obama has proposed about $1.4 trillion in new revenues over 10 years, while Boehner has offered around $800 billion. In both cases it was unclear how that would be achieved specifically.
Boehner, asked about a telephone conversation he had on Tuesday with Obama, said: "The president and I had a deliberate call yesterday and we spoke honestly and openly about the differences that we face."
Boehner then said that Obama's revenue proposal "cannot pass the House or the Senate."
He noted that the last Republican budget, passed early this year, "had no new revenue," while Obama's had $1.6 trillion.
Given that he is now offering $800 billion in new revenue, Boehner said, 'We've been reasonable and responsible in our approach to this."
But so far, Boehner has refused to give in to Obama's main demand that there be income tax rate increases on the top groups, those with annual net incomes above $250,000.