INDIAN WELLS, Calif. — Top strategists for the Koch network briefed their donors Monday about how they’re planning to allocate more than $400 million this election cycle on politics and policy.

Tim Phillips, president of Americans for Prosperity, predicted that 80 House races will be competitive on Election Day in November. He said that compares to about 100 districts that were in play during Barack Obama’s first midterms in 2010, when Republicans picked up 63 seats.

“2010 is similar to 2018 with one big difference: This year, we’re on defense,” Phillips told 550 members of the Koch network at their three-day winter seminar here. (To become a member, someone must commit to give at least $100,000 annually to Koch-linked groups.)

Phillips warned that Nancy Pelosi will become speaker of the House again if Democrats pick up 24 seats, and that Hillary Clinton carried 23 districts now represented by Republican incumbents.

He told conservative and libertarian-minded donors that they should be worried about the number of GOP lawmakers retiring in competitive jurisdictions. His PowerPoint presentation noted that there have been 15 such retirements, but Phillips clarified that the number is now 16 with New Jersey Rep. Rodney Frelinghuysen’s announcement Monday that he will not seek reelection.

“And it is only January,” Phillips said, with a wince. “I’m a liberal arts major from Virginia Tech University, and that was a long time ago. So math is not my strong suit, but I know these are daunting numbers.”

Phillips spoke alongside Emily Seidel, chief executive of Americans for Prosperity and a former staffer for Mike Pence. They followed political handicapper Charlie Cook, who went over the House and Senate maps during breakfast at a resort in the desert outside Palm Springs, Calif.

“These elections are going to be brutally tough. We’ve never faced a challenge like this one,” said Seidel. “This Senate majority may come down to a single seat.… Many are saying that 2018 will may be a wave.… We have to go all in.”

She said the network, led by billionaire industrialist Charles Koch, is currently “analyzing” 14 Senate races and has fully committed in four races where a GOP candidate shares their values and they believe a heavy Koch investment could change the outcome. President Trump carried all four of the states, and they are represented by a Democratic incumbent: Indiana’s Joe Donnelly, Wisconsin’s Tammy Baldwin, Missouri’s Claire McCaskill and Florida’s Bill Nelson.

“That list will continue to grow,” said Seidel, who added that “it’s an uphill challenge to knock off incumbents.”

Seidel outlined a two-pronged strategy to help Republicans hold the Senate: heavy early spending on television commercials to define candidates before they can introduce themselves to voters and investment in a field operation.

“It might seem like November is a long ways away, but given those two strategies, we are already in the thick of the fight,” she said.

Seidel explained that most spending on television ads happens after Labor Day, but most voters decide who they’re going to support well before those ads air. In 2016, she noted, 60 percent of voters were locked in by the end of August.

She cited Ohio as a case study to validate this approach. The network spent millions to carpet bomb Ted Strickland, the Democratic challenger to GOP Sen. Rob Portman, very early in the 2016 race. Portman opened a lead, and the network didn’t have to invest in the Buckeye State in the fall.

“Because of the permanent capabilities of this network, our sweet spot is in the first half of the year for paid media,” Seidel said. “This gives us the opportunity to influence broad swaths of the electorate as they’re making up their minds.… Paid media is less expensive and more effective earlier in the year, and then [the ground game] is more effective toward the end when we are looking to influence the undecided voters.”

Phillips told the donors that House races tend to develop later in the year than gubernatorial and Senate contests because the candidates are less known and get less attention. “So there’s a lot of clutter on the House front,” he said.

The network plans to launch “a massive direct-mail initiative” in the summer and then pivot to grass-roots efforts from the start of August through Election Day.

Seidel noted that, of the 36 states with gubernatorial elections this year, 26 are held by Republicans. She said the network is closely tracking 15 of the races and has chosen to commit in five, contesting open seats in Nevada, Michigan and Florida, as well as supporting Wisconsin Gov. Scott Walker’s bid for a third term and helping Illinois Gov. Bruce Rauner try to win a second term.

The other 10 governors’ races that that the network is monitoring are in Arizona, New Mexico, Colorado, Kansas, Minnesota, Iowa, Ohio, Pennsylvania, New Hampshire and Georgia.

“We take a businesslike approach to this,” said Seidel. “We don’t want to waste resources on a race that’s either a clear loss or a clear win. We want to make the difference.”