/ WASHINGTON — All but 13 of the 289 congressional Republicans have signed a pledge vowing to oppose tax increases. On Thursday, the author of that pledge met with some of them to help them understand exactly what it is they signed.

In the process, anti-tax activist Grover Norquist sparked a fresh barrage of criticism from Democrats who accuse him and his pledge of being one of the major impediments to a bipartisan, debt-cutting deal. Norquist and Republicans defended the pledge, denied he is hurting his party, and said gridlock on the issue is not his fault.

The pledge has been "extremely helpful" to the Republican Party, Norquist said after meeting privately with Republicans, saying the document has helped Republicans define a position that is popular with voters.

"They're not going to raise taxes to pay for Obama-sized government," said Norquist, who heads Americans for Tax Reform. "They're going to reduce Obama-sized government down to a size the American people will tolerate and are willing to pay for."

Thursday's session came at a time when some Republicans have been distancing themselves from Norquist's pledge, saying all options need to be available if a debt-reduction deal is going to be reached. The meeting also comes during an election-year fight over whether to extend expiring tax cuts for the wealthiest Americans at the end of this year, as Republicans want and Democrats oppose, and whether to overhaul the tax code.

People in the meeting said about 15 House GOP lawmakers and about 100 aides attended. The session focused on how to respond to questions about the pledge and traced its history and explained its meaning, participants said.

"There was no discussion in there today about amending anything, wiggling around or anything," said Rep. Mick Mulvaney, R-S.C.

Some Republicans such as Sen. Lindsey Graham, R-S.C., have expressed a willingness to eliminate tax breaks and use some of the proceeds to reduce deficits. That would violate a tenet of Norquist's pledge, which says any money raised that way must be used to lower tax rates.

Former Florida Gov. Jeb Bush said this month that he never had signed the pledge because he does not believe politicians should "outsource your principles and convictions to people."

Norquist said those who have signed the pledge have made a "commitment to the American people" and should "focus on the commitment they made."

Norquist has become a favorite whipping boy for Democrats. With even GOP presidential challenger Mitt Romney having signed the pledge last year, Democrats see it as the symbol — and a cause — of the GOP's refusal to back a deficit-cutting deal last summer as President Obama and House Speaker John Boehner, R-Ohio, tried to reach a compromise.

"They ought to be sitting down and working things out instead of holding court for him," said Michigan Rep. Sander Levin, the ranking Democrat on the tax-writing House Ways and Means Committee. "Norquist is here to hold feet to the fire when what we need are open minds."