The big-money groups aligned with Senate Majority Leader Mitch McConnell raised $68.3 million in 2019, a record sum for a non-election year that reflected donor support for Senate Republicans spurred by impeachment, judicial appointments and the 2020 elections, officials said Thursday.

The constellation of groups allied with McConnell (Ky.) entered 2020 with $68.1 million — a larger cash reserve than in previous cycles, according to totals provided to The Washington Post.

The majority of the money raised in 2019 came in the latter half of the year, particularly in the final two months, largely driven by the House Democrats’ impeachment inquiry, officials said.

“The enthusiasm among our donors is higher than I’ve ever seen it before, and I’ve been at this for a decade now,” said Steven Law, president and chief executive of the Senate Leadership Fund, the super PAC aligned with McConnell and Senate Republicans.

Donors were especially fired up after a November event held by the super PAC at the Trump International Hotel in Washington that featured President Trump, who highlighted the records of GOP senators up for reelection in 2020, Law said.

The super PAC and its affiliated politically active nonprofit organizations can raise and spend unlimited amounts of money, and traditionally they have enjoyed support from some of the Republican Party’s biggest donors.

In 2019, GOP donors to the groups were alarmed by proposals from the liberal wing of the Democratic presidential field and the House Democrats’ impeachment inquiry, and were pleased by McConnell’s record reshaping of the federal judiciary under Trump to ensure a conservative hold on the courts for decades to come, Law said.

Donors recognize that the Senate is “the place that ultimately holds the line, whether it’s against impeachment, against what our donors see as far-left proposals emanating from the presidential field, against whatever the current House majority pushes out,” Law said. Impeachment is “just one more instance when the Senate’s ultimate firewall role comes into focus,” he said.

Republicans have a 53-47 majority in the Senate. Democrats need a net gain of four seats to flip control of the chamber.

There are currently four toss-up Senate races for 2020, according to the Cook Political Report. In three of those, Republicans are defending their seats: Sens. Martha McSally (Ariz.), Cory Gardner (Colo.) and Susan Collins (Maine).

Sen. Doug Jones, who represents Alabama, is the only Democrat seeking reelection in a toss-up race.

Senate Democratic groups have raised enormous sums in recent years, particularly in the 2018 midterms, and some of the 2020 Senate Democratic challengers have already posted strong figures.

Among them is former astronaut Mark Kelly of Arizona, who reported raising $6.3 million in the final three months of 2019, compared with McSally’s more than $4 million.

Independent big-money groups are already running ads for the key 2020 Senate races. Senate Majority PAC, a Democratic super PAC, and affiliated nonprofit Majority Forward began airing ads late last year, and the Senate Leadership Fund has been running ads, too.

The majority of the cash on hand heading into 2020 among the Senate GOP groups was held by the Senate Leadership Fund ($30.8 million) and an affiliated nonprofit organization, One Nation ($35.5 million), officials said.

The vast majority of the total amount raised in 2019 came through two of the four groups: One Nation ($48.3 million) and the Senate Leadership Fund ($27.3 million, which includes $7.6 million transferred from One Nation), officials said. The other affiliated groups are American Crossroads, a super PAC, and Crossroads GPS, a nonprofit.

Money raised by One Nation and other politically active nonprofit groups will not be made public until after the 2020 elections, and they are not required to reveal their donors. The official 2019 fundraising figures for the campaigns and super PACs will be made public on Jan. 31, the last day to submit year-end records with the Federal Election Commission.

The big-money groups aligned with Senate Democrats have not yet released their tally ahead of the FEC filing deadline.