Senate Democrats have enlisted the help of the state’s popular former governor, Sen. Mark R. Warner, to help raise money as they head into the crucial fall elections.

Warner will headline a fundraiser for the caucus July 31 at the Virginia Center for Architecture in Richmond. Ticket prices range from $35 to $5,000.

Democrats are trying to hold onto the party’s fragile 22 to 18 majority in the state Senate.

“Nothing is more important to us this year than keeping the Senate in Democratic hands,’’ Senate Majority Leader Dick Saslaw said in an e-mail to supporters.

If Republicans are successful in upsetting the majority, it would be the second time since Reconstruction that the party held the governor’s mansion, House and Senate at the same time.

Figures from the latest fundraising period are due Friday from both parties. Gov. Bob McDonnell (R) reported nearly $3 million in the bank but Senate Republican caucus members declined to release their numbers.

Saslaw (D-Fairfax) said recently that Senate Democrats have about $1 million in the bank to give to candidates and expect to raise an additional $1.5 million before the November elections.