Senate Democrats, despite signs of increasing political vulnerability in the midterm elections, continue to be far more generous than their Republican counterparts in sending personal campaign funds to their parties’ respective campaign committees.

Through May 31, Senate Democrats had transferred $4.6 million in personal campaign and leadership political action committee funds to the Democratic Senatorial Campaign Committee for the cycle. National Republican Senatorial Committee Chairman John Cornyn (Texas) confirmed in a brief interview Wednesday that Member transfers from GOP Senators remain a very small part of his overall fundraising strategy.

The DSCC declined to release Member transfer figures for June. But committee Chairman Bob Menendez said Member giving remained brisk through end of the second quarter and was meeting expectations.

He also noted that 25 Senators stopped by DSCC headquarters Wednesday to make fundraising telephone calls. Member giving is a key part of the DSCC’s fundraising blueprint and has served to give the committee a leg up on the NRSC since 2005.

“We had a lot of Member giving — and some at very significant amounts. So we’re pleased that our colleagues continue to join in,” the New Jersey Democrat said. “There are many different ways in which I could give championship awards to each and every Member.”

The Democratic Senators who made fundraising calls at DSCC headquarters Wednesday were participating in the committee’s “power hour” program, Menendez said. Once or twice a month, Members spend time at the DSCC making fundraising calls to individual donors around the country.

Senate Republicans began this election cycle facing the prospect of more steep losses, given that the electoral map featured more incumbent GOP Members — and in swing seats — than veteran Democrats.

However, the Republicans have since turned things around to the point where some analysts are giving them an outside chance of flipping the chamber. The NRSC is targeting 11 seats and needs to win 10 to get to 51.

Cornyn said this enthusiasm hasn’t caused an uptick in Member transfers within a Conference notoriously resistant to funding the NRSC with personal and leadership PAC funds. But he said Members have been extremely generous with their time, including traveling around the country to headline NRSC fundraisers. From the outset of this cycle, Cornyn’s strategy has been to ask Members for time rather than transfers, and they have responded.

“Recognizing the reluctance of Members to transfer money out of their campaign accounts — and for, I would say, understandable reasons — we’ve emphasized the importance of participation in other ways,” Cornyn said. “Frankly, I don’t care how we raise the money as long as it gets done, and so far our fundraising is about 25 percent of where it was two years ago.”

In fact, the NRSC had more cash in the bank than the DSCC as of May 31, reporting $18.1 million on hand to the Democratic committee’s $17.6 million.

Wednesday marked the Federal Election Commission fundraising reporting deadline for the crucial second-quarter filing period.

With the Nov. 2 elections just four months out, finishing June in a strong financial position is key to a Congressional campaign committee’s ability to buy early television advertising time at discounted rates and create momentum among individual and activist community donors nationwide heading into the fall. And with the monthlong August recess set to begin in about four weeks, time is running out to squeeze significant transfer dollars out of Members.

Among the 58-Member majority, figures through the end of May show that 18 Senators had transferred $100,000 or more to the DSCC, with six giving at least $200,000 and three contributing at least $300,000. Commerce Chairman Jay Rockefeller (W.Va.) was tops in Member giving to the committee at the end of May, having transferred $342,000.

Senate Majority Whip Dick Durbin (Ill.), who is carrying much of the campaign load for the Democratic leadership team while Majority Leader Harry Reid (Nev.) wages an uphill battle to save his job, wasn’t far behind at $330,000. Reid had transferred $30,000 to the DSCC, as had Conference Vice Chairman Charles Schumer (N.Y.) and Conference Secretary Patty Murray (Wash.), who are both up for re-election. Menendez had also given $30,000.

Menendez also noted that Senators helped the party in many ways other than direct giving. He pointed to Energy and Natural Resources Chairman Jeff Bingaman (N.M.), who has traveled a great deal to raise money for the DSCC.

“We have Members who travel extensively for us, like Sen. Bingaman. We have Members who’ve had very significant giving to us, and there are several in that category,” Menendez said.

For Senate Democrats, other big givers include Finance Chairman Max Baucus (Mont.), who had transferred $250,000 to the DSCC since Jan. 1, 2009; Budget Chairman Kent Conrad (N.D.), who had given $315,000; retiring Sen. Byron Dorgan (N.D.), who had donated $270,000; Homeland Security and Governmental Affairs Chairman Joe Lieberman (ID-Conn.), who had contributed $240,000; and Health, Education, Labor and Pensions Chairman Tom Harkin (Iowa), who had transferred $215,000.

Additionally, Intelligence Chairman Dianne Feinstein (Calif.) had given $171,000; Armed Services Chairman Carl Levin (Mich.) had donated $150,000; Appropriations Chairman Daniel Inouye (Hawaii) and Foreign Relations Chairman John Kerry (Mass.) had each contributed $130,000; and rank-and-file Sen. Mark Pryor (Ark.) had transferred $155,000.

Other notable DSCC transfers included a paltry $5,000 given by Veterans’ Affairs Chairman Daniel Akaka (Hawaii) and $15,000 contributed by retiring Sen. Evan Bayh (Ind.), who is sitting on about $10 million.