Democrat Danica Roem, left, is challenging longtime incumbent Del. Robert Marshall (R-Prince William), right. (Steve Helber/AP)

Del. Robert G. Marshall (R-Prince William) has received a late-stage infusion of cash from Virginia Republican leaders, which one expert said suggests the state party is worried about losing the seat he has held for nearly 26 years.

During the past three weeks, political action committees tied to likely incoming House of Delegates Speaker M. Kirkland Cox and former speaker William J. Howell contributed a total of $75,000 toward Marshall’s campaign to defeat Democrat Danica Roem, who has outraised him 3 to 1 and is running a strong grass-roots effort to become the first openly transgender elected official in Virginia.

Several of Marshall’s fellow Republican delegates also made contributions, totaling $7,000, while the state party assisted his campaign with direct mailings and other “in-kind” donations worth about $22,800.

That money — plus another $50,000 Marshall received from conservative groups and individual donors in October — will go toward a last push for votes before the Tuesday contest, which has taken an uglier turn in recent weeks with ads by Marshall that focus on Roem’s transgender identity and accuse her of “lewd behavior.”

The Republican Party’s last-minute support — to a renegade member who in the past has repeatedly alienated party leaders — could reflect concern about losing a key foothold in Northern Virginia as Democrats try to gain ground in the Republican-held General Assembly, said Stephen J. Farnsworth, a political-science professor at the University of Mary Washington in Fredericksburg.

Democrat Danica Roem and Del. Robert Marshall (R-Prince William). (J. Lawler Duggan For The Washington Post; Steve Helber/AP)

“One of the best ways to know what races a party is concerned about is to look for big donations in late October,” Farnsworth said. “The money that’s come into Marshall these past few weeks suggests that there is a good deal of concern and that this race is uncomfortably close from the Republican perspective.”

Marshall, who has run a mostly low-profile campaign in which he has refused to debate Roem or allow reporters to accompany him on the campaign trail, replied to requests for comment with a statement. “I’m thankful the party organizations have stepped up to support me against the many out-of-state dollars my opponents has raised,” he said.

Roem has collected nearly $500,000 overall, with much of it coming from national LGBT groups and other progressive organizations.

Marshall, who tried unsuccessfully this year to pass a “bathroom bill” that would have regulated which restrooms transgender people can use inside government buildings, has also received large contributions from outside Virginia, including $20,000 from Sean Fieler, a New Jersey hedge fund manager who also chairs the conservative American Principles Project, records show.

The support he has received from Virginia Republicans comes after years in which Marshall, known for his unyielding opposition to abortion and same-sex marriage, has alienated his party’s leadership.

In 2007, Marshall introduced a resolution of “no confidence” against Republican leaders, complaining that they were too willing to allow government spending to increase. The following year, Marshall successfully sued to kill a bipartisan transportation funding law. The Supreme Court of Virginia found the law unconstitutional because it granted taxing authority to regional authorities that had unelected board members.

A spokesman for Cox said the party isn’t worried about Marshall losing and called the recent donations part of a broader effort to support several candidates. In October, the Colonial Leadership Trust PAC donated a total of $226,500 to six Republican candidates, including a $50,000 donation to Marshall, according to the nonprofit Virginia Public Access Project.

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But Farnsworth said recent efforts by Marshall and the state party to highlight Roem’s transgender identity show that Republicans are trying to motivate more of their base in the 13th District to vote on Tuesday.

Roem — who received $60,000 in cash from the state Democratic Party in October, plus $63,000 in in-kind donations — called the GOP donations to Marshall disingenuous, considering the fact that, in recent years, most of his bills have languished in committee in the majority-Republican General Assembly.

“I thought it was really funny that the same party that killed 27 of his 30 bills this year is now trying to bail him out during the last month of the campaign,” Roem said. “But it’s far too late.”