K Street’s most generous political donors paid out a record sum during the 2016 campaign cycle, and many of them say they are already opening their wallets for next year’s elections despite fatigue at the pace of fundraising requests.

“I’m writing those checks a little more reluctantly — the hand is sort of shaking more than it used to,” said lobbyist Larry O’Brien, a longtime top donor to Democrats, only half-joking.

O’Brien, whose recent clients at his OB-C Group include Honeywell International and the Everytown for Gun Safety Action Fund, gave more than $230,000 to Democratic candidates and committees in the last cycle. He said he’s already donated nearly $70,000 toward the 2018 elections.

The top federal lobbyists who typically donate to campaigns have been increasing their total contributions in recent cycles, fueled largely by bigger limits. The 25 biggest lobbyist donors, alone, gave $5.3 million in the 2016 cycle, according to the nonpartisan Center for Responsive Politics, which tracks lobbying and political money.

A presidential contest typically attracts more political donors, but the 2016 cycle also featured several competitive Senate races with majority control on the line.

The giving to campaigns by the 25 biggest lobbyist donors last year compares with $4.3 million in 2014, $3.6 million in 2012 and $3.1 million in 2010. The Supreme Court’s January 2010 decision in Citizens United v. Federal Election Commission helped pave the way for super PACs, which can raise an unlimited amount of money from wealthy individuals and unions.

And in another case, McCutcheon v. FEC in 2014, the high court rolled back aggregate limits on donations to federal candidates.

The top donating lobbyist in the 2016 elections gave nearly $400,000 in the 2016 elections, which may seem puny when compared with the mega-millions spent on politics last year by Democrat Tom Steyer and Republican Sheldon Adelson, both billionaires. But among all U.S. adults, fewer than 1 percent gave $200 or more to federal candidates, according to the center’s data.

Presidential candidates and congressional leaders have also increasingly used joint fundraising committees as a way to solicit more money from big donors, including lobbyists.

“The changes to the rules have provided for ways to give more, and with lobbyists, there is always a built-in benefit to making political contributions,” said Sheila Krumholz, executive director at the Center for Responsive Politics. “These are investments in their career.”

She sees no reason for a K Street donating ebb in 2018.

Lobbyist Heather Podesta doesn’t either, even though her presidential pick, Hillary Clinton, and some of her preferred Senate candidates lost last year. Her bipartisan firm, Heather Podesta + Partners, has hosted fundraisers this year, as early as January.

She encourages female donors, including those at the beginning of their career, to donate, Podesta said.

“Writing a check or raising funds brings you to the table in a different way than door-knocking does,” said Podesta, whose registered clients recently have included PepsiCo and Uber Technologies. “You’re just more closely connected with issues and people.”

Women, Podesta added, have traditionally been the “doers” of the Democratic Party, organizing and canvassing for candidates. “It’s really time for all of us to step up and be funders as well,” she said.

Democrats received the bulk, almost 60 percent, of donations from K Street’s biggest donors in the 2016 cycle. And very few registered lobbyists gave money to the presidential effort of Donald Trump.

An exception is Van Hipp Jr., a lobbyist with American Defense International who donated $50,000 to the Trump Victory joint fundraising committee. Hipp was among the 20 biggest donors among registered lobbyists in the 2016 cycle.

“I’m probably one of the few in D.C. who got on the Trump train early,” said Hipp, whose registered clients last year included Clemson University. “I wear that as a badge of honor.”

Lobbyists whose candidates were on the losing end, though, say they don’t view it as a bad investment.

“It’s disappointing when people you believe in and that are friends lose, and it has everything to do with the leadership that they won’t be able to exert at this moment,” Podesta said. “I believe strongly in having no regrets and helping good people.”

Democrats will be on defense in the Senate in 2018, when 10 senators are up for re-election in states that Trump won. Republican lobbyists say they are motivated to help expand their party’s 52-48 voting advantage in the chamber, while Democrats believe controversies around the Trump administration could put control of the House in play.

“There is so much energy out there,” said Steve Elmendorf, a Democratic lobbyist and the biggest K Street donor. His clients at his firm, Subject Matter, include UnitedHealth Group and MetLife.

“In ’18 the stakes are very high, and it’s really important to have a check on Trump,” Elmendorf said. “The pressure to give never goes away.”