National Democrats are directing millions of dollars into Kansas to support Senate candidate Adam Hamilton, a nominee who has built much of his campaign around the claim that he would not answer to the party's top leaders in Washington.

A sizable share of the money is coming from Senate Majority PAC, a super PAC closely aligned with Senate Minority Leader Chuck Schumer, D-N.Y. Hamilton has said repeatedly that he would not support Schumer as Democratic leader if he wins in November.

His Republican opponent, Sen. Roger Marshall, questioned how that could be true. He asked how Hamilton could take in "$30 to $40 million from Chuck Schumer and not be beholden to him in some way?"

Marshall made the case to Fox News Digital during an interview on the campaign trail. "Regardless of what he says, if we lose this seat, then it's going to give the Senate control to the Democrats," he said. "Chuck Schumer would be the leader of the Senate." He also said Republicans expected to be outspent five to one.

Federal election law bars candidates from directly accepting outside funding from independent groups such as Senate Majority PAC, according to the Federal Election Commission. The group reserved $5 million in Kansas advertising earlier this month, a sign Democrats are optimistic about flipping a seat in a race that has tightened more than Republicans anticipated.

Hamilton's campaign countered that Marshall, a first-term senator, has been thrown a lifeboat by national Republicans. Federal Election Commission filings show Hamilton has raised nearly $14 million, compared with almost $6 million for Marshall.

"Adam has said repeatedly he believes it's time for fresh leadership in Washington," campaign spokesperson Tyson Brody told Fox News Digital. He added that Hamilton "will always put Kansas first," and accused Marshall of depending on Washington money after abandoning Kansas to support "D.C. corruption, endless war and high prices."

According to AdImpact, national Democrats and affiliated groups, together with Hamilton's campaign, are expected to spend $38 million on the race. National Republicans and Marshall's campaign are putting in $32 million.

Marshall has tried to link Hamilton, who is running as a moderate in solidly Republican Kansas, directly to Schumer. He raised the point several times during their final debate before Election Day. Hamilton responded that Marshall had brought up Schumer "maybe 20 times so far." He repeated his position: "I've already said I wouldn't support Chuck Schumer for Senate majority leader if the Democrats took control of the Senate."