Republican Senate candidate Josh Hawley of Missouri appears to be distancing himself from the state's embattled governor.
Trump is scheduled to attend a private fundraiser for Hawley Wednesday in St. Louis.
Hawley campaign consultant Brad Todd told reporters not to expect fellow Republican Gov. Eric Greitens on the campaign trail during kickoff events. "She has 36 years of special interest political chits that she has collected".
In an appearance at a Raytown warehouse of a commercial construction supplier, Hawley said he looks forward to having the president's support throughout the campaign. "We're going to fight every way we can to raise the resources that we need".
McCaskill, who Hawley lambasted as a career politician beholden to the liberal elite, Wall Street and Hollywood, is seen as one of the most vulnerable incumbents as a Democrat in a state won by Trump by almost 20 percentage points in 2016.
A grand jury indicted Greitens on a felony invasion-of-privacy charge last month related to a 2015 affair.
"We need to have that power", Hawley said.