WASHINGTON — The senior Democrat on the House Judiciary Committee yesterday protested President Bush's re-election with a new report claiming serious election irregularities and "significant disenfranchisement" of voters in Ohio.

The report by Rep. John Conyers of Michigan says the Electoral College vote should be challenged when it is tallied today in the House and all claims of voter problems in Ohio should be investigated.

"We have found numerous, serious election irregularities in the Ohio presidential election," the report said. "There are ample grounds for challenging the electors from the state of Ohio."

Ohio's 20 electoral votes were decisive in Bush's defeat of Democrat John Kerry. A recount showed Bush winning Ohio by 118,599 votes, the Ohio Secretary of State's Office announced yesterday.

The 102-page report lists such problems as unusually long lines, a shortage of voting machines in Democratic-leaning areas, confusion over provisional-ballot rules and computer problems.

The report also contends there was intimidation and misinformation, improper purging of voter-registration lists, a lack of inspection for about 93,000 ballots where no vote was cast for president, and vote totals not matching registration numbers or exit-poll data.

"In many cases, these irregularities were caused by intentional misconduct and illegal behavior, much of it involving Secretary of State J. Kenneth Blackwell, the co-chair of the Bush-Cheney campaign in Ohio," the report said.

Carlo LoParo, a spokesman for Blackwell, called the report "ludicrous" and a waste of time and taxpayer dollars.

"There are absolutely no grounds for challenging Ohio's electors," LoParo said. Meanwhile, several House Democrats were looking for a senator to co-sponsor their challenge of Ohio's electoral votes.

The report was sent with a letter signed by 24 House Democrats to Senate leaders, claiming that the "massive and unprecedented extent of irregularities in Ohio raise grave doubts" about the state's electoral votes.

A single senator supporting the effort by law would require the two chambers to meet separately for up to two hours and consider the objection. Democratic aides said Sen. Barbara Boxer, D-Calif., might support such a move.

That scenario still would ensure Bush's re-election because both Republican-controlled bodies would have to uphold the challenge for it to succeed. Supporters of the challenge are hoping to call attention to the Ohio voting problems.

In a letter to supporters yesterday, Kerry said he would not take part in a formal protest of Ohio electors because, despite reports of voting irregularities, his legal team had "found no evidence that would change the outcome of the election."

Kerry said he planned to introduce election-reform legislation and push for congressional hearings on the voting irregularities.