Shumer does not see enough evidence:

[rumpel]

Some Democrats have complained that voting problems in Ohio, where Bush won by more than 118,000 votes, deserve closer scrutiny.
Others in the party believe the objections may anger voters and make Democrats look like sore losers.
"My view is that you don't hold up the election unless there is concrete real evidence of fraud. I haven't seen that," Schumer said Thursday.
In contrast, Sen. Hillary Rodham Clinton, D-N.Y., took to the Senate floor to thank Boxer for her move, saying the government needs to set higher standards for voting accuracy.
"As we look at our election system, I think it's fair to say that there are many legitimate questions about its accuracy, about it's integrity, and they are not confined to the state of Ohio," said Clinton, considered an early Democratic frontrunner for the 2008 presidential race.

and then

"Chuck certainly thinks that the problems our nation has in voting are worth two hours of the Senate's attention, but he doesn't believe we should stop the certification of the election for that purpose, and every senator except Senator Boxer agreed with him," said Schumer spokesman Stu Loeser.
In the House, three New York City Democrats, Reps. Anthony Weiner, Jose Serrano, and Major Owens, had supported the initial Ohio objection. Of those three, only Owens still voted against the election results after the debate, as did Rep. Maurice Hinchey, who represents the Hudson Valley.
Upstate Republican Thomas Reynolds, R-Clarence, ripped Democrats for making a stink in the quadrennial electoral ritual.

from:

http://www.newsday.com/news/local/state/ny-bc-ny--schumer-electoral0106jan06,0,2540056.story?coll=ny-region-apnewyork