As Trump ramps up his revenge tour against the House Republicans who voted to impeach him, GOP lawmakers are sounding the alarm that his attempts to meddle in primaries could hurt the party’s efforts to win back the House next year, especially in critical swing districts in New York, Michigan and California. With just five seats between the GOP and the House majority, any one race could determine the balance.

The loudest warning shot came Wednesday from Minnesota Rep. Tom Emmer, the head of the National Republican Congressional Committee, who told POLITICO Playbook he planned to urge the former president to refrain from playing in primaries. “That’s not going to be helpful,” he said. “It’s probably better for us that we keep these people.”…

With anxiety running high behind the scenes, Emmer has been calling the House Republicans who voted to impeach Trump and privately assuring them that the party will have their backs, according to two GOP sources familiar with the conversations. The NRCC has a longstanding policy to not get involved in primaries, even for incumbents. But the campaign arm can be helpful in other ways to the campaigns of members who pay their dues, such as providing assistance on digital fundraising and recommending certain vendors.