Talks to avert the so-called “fiscal cliff” took a turn for the worse Wednesday as President Barack Obama accused Republicans of holding a personal grudge against him while the top GOP negotiator called the president "irrational."

As a year-end deadline nears, Obama and House Speaker John Boehner, R-Ohio, are locked in intense bargaining over a possible deal to avoid sudden tax hikes and automatic spending cuts that could badly damage an already weak economy.

Obama said he was puzzled over what was holding up the talks and told Republicans to stop worrying about scoring "a point against the president" or forcing him into concessions "just for the heck of it," Reuters reported.

"It is very hard for them to say yes to me," he told a White House news conference. “At some point, you know, they've got to take me out of it."

The president also blasted Boehner and the House GOP for refusing to negotiate in good faith.

“Frankly, up until about a couple of days ago if you looked at it, the Republicans in the House and Speaker Boehner, I think, were in a position to say we’ve gotten a fair deal,” Obama said. “The fact that they haven’t taken it yet is puzzling, and I think, you know, a question that you’re going to have to address to them. … I think anybody who looks at this objectively will say that coming off my election, I have met them at least halfway in order to get something done for the country.”

The rise in tensions threatens to unravel significant progress made over the last week.

Boehner and Obama have each offered substantial concessions that have made a deal look within reach. Obama has agreed to cuts in future Social Security hikes, while Boehner has conceded to Obama's demand that taxes rise for the richest Americans.

But the goodwill has evaporated since Boehner announced plans on Tuesday to put an alternative tax plan to a vote in the House this week that would largely disregard the progress made so far in negotiations.

On Wednesday, Obama threatened to veto the Republican measure, known as "Plan B." It is unlikely he would need to, since Senate Democrats have declared it dead on arrival.

Boehner's office slammed Obama for opposing their plan, which would raise tax rates on households making more than $1 million a year and is a concession from longstanding Republican opposition to increasing any tax rates.

"The White House's opposition to a backup plan ... is growing more bizarre and irrational by the day," Boehner said through his spokesman, Brendan Buck, Reuters reported.

Boehner, however, faces discontent from the right in his own caucus, where many are reluctant to vote for any tax increase on anybody.

Politico reported Wednesday night that the leadership is considering attaching a package of spending cuts to Boehner’s “Plan B.” Republican lawmakers are skittish about voting on allowing taxes to snap to near 40 percent for millionaires without paring back federal spending.

Simultaneously, the Republican leadership scrapped a plan to vote on the Senate’s tax rate proposal, which extended Bush-era tax rates for income below $250,000 – which was Obama original position.

Obama said he is willing to continue talks with Boehner. But the two have not spoken since Monday night, when the speaker informed him of the alternate strategy, Politico reports.