WASHINGTON — A bipartisan spirit of cooperation in Congress following last year’s Boston Marathon bombing dissolved into partisan rancor Wednesday, with all but one Democrat on the House Committee on Homeland Security refusing to endorse the committee’s report documenting intelligence failures.
Top committee Democrats complained that Republicans who run the committee excluded them from deliberations over which classified information to include in the report.
Furious Republicans said Democrats’ complaints were baseless and blamed them for inserting partisanship into the official investigation on the Marathon bombing, which killed three people and injured more than 260. They said Democrats were involved in researching, crafting, and editing the report and that classified sections were removed after Democrats’ protests.
“They’re playing a dangerous game if they want to politicize this deal because it’s a very serious report that we spent an incredible amount of time with the Democrats participating fully,” said the committee chairman, Michael McCaul of Texas. “For them to say this makes no sense to me.”
He said the committee removed sections in the report that drew Democrats’ complaints. The committee spokeswoman, Charlotte Sellmyer, added that the report had been cleared by the National Counterterrorism Center — meaning key intelligence agencies had signed off on classified material. She also noted that Democratic committee staff had traveled to Russia to help research the committee’s findings.
Representative William R. Keating, a Bourne Democrat and the only Massachusetts member of the committee, was the sole member of his party to break ranks and sign on to the report.
“The last thing that the family members and people that were injured — and family members of the victims — the last thing they want to see is any kind of internal issues surfacing,” Keating said.
Keating said he had “zero tolerance” for the congressional infighting and maintained that he was intimately involved in preparing the report.
But the dissent from other Democrats could blunt the impact of the report. Instead of issuing a report that carries the weight of the full committee, McCaul said he was releasing the “McCaul-Keating” report. Six other key Republicans also signed the report.
“It’s a Republican-produced document,” said Loretta Sanchez of California, the second-ranking Democrat on the committee.
She and Bennie G. Thompson of Mississippi, the top Democrat on the committee, insisted they had not even read it. Thompson said Republicans were supposed to allow the full panel to review and decide whether to use classified data in the report and then allow relevant agencies to review it.
“I said to the chairman, ‘You will have to produce a report produced by the majority because we are not going to operate outside the rules of the committee,’” Thompson said.
He added that the use of classified information could pose a problem for federal prosecutors in their case against Dzhokhar Tsarnaev.
“We don’t want to compromise the prosecution of the suspect in Boston,” Thompson said.
Another Democrat, Representative Yvette D. Clarke of New York, drew on the report’s conclusions that the nation’s security depends on better coordination from public officials and law enforcement.
“The Homeland Security Committee should demonstrate the same commitment to coordination between Democrats and Republicans who share the same purpose of protecting our nation and its people from a terrorist attack,” she said.
But Representative Mike Rogers, an Alabama Republican and senior member of the committee, said he worries the dispute will take attention from the outstanding performance of first responders at the Marathon finish line last year.
“I don’t want that to get no attention because we’re fussing over some pettiness,” Rogers said.
Matt Viser of the Globe staff contributed to this report. Noah Bierman can be reached at email@example.com.