WASHINGTON – Senate and House Democrats, optimistic about their election-year prospects, have more money in the bank for the midterm contests than their Republican counterparts.

Some four months before the voting, the Democratic Senatorial Campaign Committee has $33.5 million cash on hand compared to $18.3 million for the National Republican Senatorial Committee, the groups said yesterday. The Democrats raised $4.7 million in May; the Republicans collected $4.3 million in the month.

“Our fund-raising success reflects a deep desire for change and recognition that the best way to get things back on track is by electing more Democrats to the Senate,” said Senator Schumer, chairman of the Democratic committee.

Although the GOP committees trail in cash on hand, it has the advantage of the presidency and the fund-raiser in chief as well as majority control of the House and Senate.

On Monday, Mr. Bush helped Republicans raise $27 million for the fall congressional contests, with $15 million for Senate candidates and $12 million for House candidates. The numbers will be reflected in the next filing. The president used the event to reassure Republicans that they will prevail in November.

“We’re going to keep the House and we’re going to keep the Senate thanks to all of you here,” Mr. Bush said.

House Democrats said they had $24.5 million cash on hand after raising $5.5 million last month. House Republicans said they had $21.9 million at the end of May after collecting $5.6 million.