WASHINGTON (AP) — The White House has a message for vulnerable House Republicans tiptoeing around President Donald Trump: Get on board or start packing.

The warning comes in a memo from White House political director Bill Stepien, who argues that GOP candidates who try to distance themselves from the president are only doing themselves harm in the upcoming midterm elections.

The memo, dated Monday and obtained by The Associated Press, serves as a response to a grim White House briefing by pollsters for the Republican National Committee last month regarding GOP midterm prospects. It also previews some of Trump's upcoming travel just as White House officials are eagerly noting the president's efforts to help beleaguered House candidates, not just contenders in more prominent Senate races.

Midterm elections are traditionally difficult for the parties of incumbent presidents, and this year is proving to be no exception. The GOP is facing down considerable Democratic enthusiasm as it looks to retain control of the House and Senate. But the White House memo argues that public perceptions about whether the country is on the right track temper the probability of a Democratic wave. So do redrawn congressional districts, which have reduced the number of contested seats.

"With Americans supporting the direction of the country at historically high levels — but with Republican voters clearly lagging in enthusiasm — the path forward is clear; Republican candidates need to closely, clearly and boldly align themselves with the policies that have provided Americans with this historic level of directional optimism," Stepien wrote.

The White House memo suggests that countering the enthusiasm gap is where Trump can make up the difference — for those candidates willing to take his help. Republicans who don't talk about Trump or his accomplishments, the White House warns, will make a tough situation a whole lot tougher.

Trump has used campaign rallies in an effort to boost Republican turnout, encouraging the voters he drew to the polls in 2016 to support more staid traditional lawmakers. Both parties largely view the 2018 contest as a race to turn out party faithful rather than an effort to attract new voters. At a rally in Southaven, Mississippi, on Tuesday, Trump told voters: "Pretend I'm on the ballot."

He added: "This is also a referendum about me and the disgusting gridlock they'll put this country through."

That message is consistent with the advice given last month to White House staff by GOP pollster Neil Newhouse, who said Republicans need to warn of the consequences if Democrats gain control of either chamber of Congress. He told White House officials that Trump could appeal to moderates and independents by emphasizing that a Democratic majority would be outside the mainstream on issues like abolishing Immigration and Customs Enforcement and pushing government-funded health care.

Ever since, both themes have taken on more prominence in Trump's rallies.

Trump will campaign Thursday for Republican Rep. Jason Lewis of Minnesota, who invited Trump to appear on his behalf. Officials contrasted Lewis' request in the state's 2nd Congressional District with that of Republican Rep. Erik Paulsen of the neighboring 3rd District who has kept his distance from Trump. The White House believes Paulsen's rejection of Trump will sink his candidacy.

The Stepien memo states that Trump's travel strategy in the five weeks through Election Day will be to spend time with candidates like Lewis. On Saturday, he will campaign for Republican congressional candidate Steve Watkins in Kansas, kicking off a stretch of five rallies in eight days for candidates in Iowa, Pennsylvania, Ohio and Kentucky.

"Watch closely where the president has and will campaign; you will see the president aggressively campaigning in districts with candidates who enthusiastically embrace the policies that have put America on the pathway to prosperity," the memo states. "President Trump continues to be ready, willing and able to put the power and force of his coalition to work for the candidates with whom he stands, and those who stand with him."

Officials acknowledge that Florida Rep. Carlos Curbello and Texas Rep. Will Hurd, among others, are keeping difficult races competitive while still keeping their distance from the president. But they cast those races as the exceptions to the embrace-Trump rule.