Several big-money Republican donors and their networks spent millions during the 2016 election cycle to back candidates other than Donald Trump, though in the end, obviously, not only did he win the party’s presidential nomination, but he went on to defeat Hillary Clinton.

Some of them, including Paul Singer, Ken Griffin, Joe Ricketts and Stephen Schwarzman, spent big early on in the current GOP primary cycle, but that funding has largely dried up when Trump reemerged as the heavy favorite, running away from the closest Republican competitors by as much as 50 points in some surveys, The Wall Street Journal reported on Wednesday.

This election cycle, they initially began funneling money to Trump’s primary challengers, though not nearly at levels seen during the 2016 race. However, they have turned off the cash flow to the former president’s opponents because they see his 2024 nomination as inevitable at this juncture.

“It’s becoming clear the cavalry’s not coming,” Ken Spain, a longtime GOP strategist who advises the business interests about Washington, told The Wall Street Journal. “The donor community has come to recognize the strength of Trump and the difficulty in dislodging a major part of the base from him. You’re tilting at windmills if you try.”

The WSJ added:

Rob Collins, who co-chairs a super PAC supporting South Carolina Sen. Tim Scott, wrote in a new memo to donors that it was making a move that “would be obvious in the business world” by canceling much of its planned advertising this fall.

“This electorate is locked up,” he wrote, according to a copy of the document reviewed by The Wall Street Journal, adding that Republicans who oppose Trump would be “wasting money” until the GOP field thins.

It’s possible that the GOP donor group will see if someone other than Trump makes a strong finish during the first-in-the-nation Iowa caucuses in January and then throw millions at their campaign, one source told the WSJ. But even that isn’t likely given the fact that Trump appears to be unbeatable again.

“One person who works closely with several donors in the financial industry predicted that big GOP money would largely be absent from the presidential race and instead flow toward an effort to win Republican control of the Senate,” the WSJ added.