BOSTON — Gloucester attorney Edward O'Reilly has cleared an important hurdle in his bid to challenge U.S. Sen. John Kerry, filing with state officials nomination papers containing more than 11,636 signatures.

O'Reilly, a Democrat, on Wednesday turned in more than the minimum 10,000 signatures required of U.S. Senate candidates and submitted them nearly a month before the June 3 deadline.

"This shows I'm serious," O'Reilly said.

Since announcing his candidacy last year, O'Reilly has crisscrossed the state, meeting voters in more than 110 communities and collecting signatures. He also hired Spoonworks, a Brookline firm that gathers signatures for political candidates.

O'Reilly said some people would pass by him or other signature gatherers until he said he was a Democrat challenging Kerry.

"There was a tremendous positive response from people when they found out there was a Democrat running against John Kerry," O'Reilly said. "They turn around and come back."

So far, O'Reilly and Kerry are the only candidates to submit signatures, according to Brian McNiff, a spokesman for the Secretary of State. Jim Ogonowski of Dracut and Jeff Beatty of Harwich are running for the Republican Party nomination. The winner of that contest will face off against Kerry or O'Reilly in November.

The signatures candidates have to submit must be verified by clerks at the cities and towns where they were collected. O'Reilly said he was able to get his signatures in early to the Secretary of State by verifying them as he gathered them. He personally delivered the signatures Wednesday afternoon.

Having the minimum number of signatures doesn't mean he is automatically on the Democratic primary ballot. Party rules require that O'Reilly receive the vote of at least 15 percent of the delegates at the June party convention in Lowell.

O'Reilly, a former city councilor and School Committee member, has said he is confident he can overcome that 15 percent barrier.

He also heads toward the convention with significantly less money than Kerry. O'Reilly closed the first quarter, which ended March 31, with $294,000 cash on hand, while Kerry reported having $9.5 million.

O'Reilly so far has loaned his Senate campaign $383,000 while taking in $48,000 from individual donations. He also is prepared to tap a $400,000 line of credit. O'Reilly expects it will cost as much as $2 million to defeat Kerry.