Twenty-six senators raced in and out of the Ronald Reagan Republican Center last week with varying enthusiasm for a most-often-dreaded, but necessary, activity: fundraising.

Inside the National Republican Senatorial Committee’s marathon call day, even the GOP’s weakest fundraisers were on hand to dial for dollars to help the party gain the net six seats necessary to win the majority.

“I’m not real good at it, asking people to give money,” said Sen. Jeff Sessions of Alabama, who had one of the lowest fundraising hauls in the second quarter. “But I do, because it’s just part of it. People are nice when you talk to them. They understand the process.”

South Dakota Sen. John Thune made it look easy. He strolled in just after a vote, took a seat toward the back and placed a plastic cup of lemonade and bag of Nutter Butter cookies on the table. With the phone to his ear, he leaned back in his chair and said, “Hey, Al, how’s it going?” Al did much of the talking.

More than half of the caucus stopped in July 18 to fundraise for the NRSC, and CQ Roll Call was given exclusive access to the marathon call session.

The effort to get more senators personally involved was intended, in part, to help reverse a trend. Recently, Democrats have been far more generous in committee donations out of their personal campaign accounts.

In the 2012 cycle, 20 of the Democratic Senatorial Campaign Committee’s top 25 largest contributors were senators’ campaigns, and they gave a total of $8.6 million, according to figures compiled by Political MoneyLine. By comparison, nine of the NRSC’s top 25 contributors were senators’ campaigns and collectively gave just more than $1 million. Many of the GOP’s top donations came from joint fundraising committees.

Seated in four rows of two, the dialers knew exactly where they stood. A running tally of their fundraising that day was plastered prominently on a projection screen at the front of an expansive room just beyond the lobby.

Lined with black-framed state maps featuring the president’s disapproval ratings, the room is normally reserved for large meetings, reporter briefings and fundraisers. But on this day, eight rectangular tables draped in yellow were topped with a phone and stack of tip sheets and talking points. A couple of young aides sat at a table to the side updating the leader board — and switched screens as a reporter scribbled down names and dollar figures.

A few Senate candidates took part in the process as well. Louisiana Rep. Bill Cassidy, who is challenging Democratic Sen. Mary L. Landrieu, phoned a donor, thanked him for giving to his campaign this year and asked for another donation — this time for the NRSC.

“As generous as you’ve been with us,” he said, “they’re wondering if you’re willing to re-up your Majority Maker status. That’s going to cost you $32,400.”

According to a tip sheet that lay on a table, a “Majority Makers” membership offers donors two tickets to monthly dinners and the NRSC’s fall political victory conference. A “Senatorial Trust” membership sets donors back $15,000 per year.

Other reference notes provided for senators included a list of the top seven targeted seats and the Republicans running for them. The only one viewable was Alaska Lt. Gov. Mead Treadwell, who is one of two Republicans vying to challenge Democratic Sen. Mark Begich.

Initially, Sen. James M. Inhofe led his colleagues with more than $127,000 raised on behalf of the NRSC. But the Oklahoma senator wound up finishing third after a late surge by Utah Sen. Orrin G. Hatch and Cassidy.

It wasn’t so easy for some of their colleagues. Wyoming Sen. Michael B. Enzi wore his discomfort on his sleeve — he was the only senator CQ Roll Call saw who didn’t take off his suit jacket.

Enzi also made his way to a smaller call room upstairs to beef up his own anemic fundraising. After tying for the lowest second-quarter fundraising in the Senate, Enzi must bag more cash to fend off a primary challenge from Liz Cheney, the elder daughter of former Vice President Dick Cheney.

The NRSC’s event raised $1.2 million, according to a committee spokesman. That number could help Senate Republicans close the gap this month with the DSCC, which has outraised the NRSC in five out of six months. A DSCC spokesman said the committee has held a call day this year as well.

“This is the first time since I’ve been the chairman that we’ve had a concerted effort,” Moran said. “It’s easier to do things whenever it’s done as a group. … There’s a little peer pressure when everybody else is coming, that more people agree to do it.”

The date for the closed-door telethon was set far in advance. But the timing couldn’t have been better, coming just days after former Montana Gov. Brian Schweitzer opted against a Senate bid there.

The Democrat’s decision gives Republicans another opportunity to pick up a seat, as well as a stronger case to make to donors about the possibility of taking control of the Senate in 2014.

“That makes it easier,” Moran said. “Senators, as well as voters and donors, get enthused whenever the opportunities look like they’re getting better.”

As she rushed out for a ride to the Capitol with Sen. John Barrasso of Wyoming, New Hampshire Sen. Kelly Ayotte credited Moran with “bringing a real team spirit to making sure we have the resources to take the majority in the Senate.”