In her bid to become Virginia's next lieutenant governor, Republican state Sen. Jill Holtzman Vogel campaigns as an ethics attorney who represents charities and nonprofit organizations.

But her firm's specialty is helping wealthy donors, corporations and political action committees influence elections — often in secret.

Vogel and her boutique law firm represent some of the nation's largest super PACs and their related nonprofits, which are often called "dark-money" groups because they are not legally required to disclose the names of their donors.

Those entities include American Crossroads, the super PAC conceived by Republican gubernatorial candidate Ed Gillespie and strategist Karl Rove, as well as Americans for Prosperity and other arms of the conservative political network founded by billionaires Charles and David Koch.

Those groups took off in the wake of the Supreme Court's 2010 Citizens United decision, which found individuals, corporations and unions could spend unlimited sums on politics as long as they did so independently of campaigns and parties.

And Vogel's firm — Holtzman Vogel Josefiak Torchinsky PLLC, known as HVJT — became one of the premiere legal shops to help the PACs distribute their largesse.

Between 2005 and 2016, PACs and nonprofits that have hired Vogel's firm spent close to $1 billion on federal elections, representing nearly a quarter of all outside spending over that period, according to data compiled by the Center for Responsive Politics. For the 2016 cycle alone, those organizations accounted for more than $234 million of $1.4 billion in total outside spending.

Critics say Vogel's firm profits from a national problem — untraceable money in politics that is corroding democracy.

"They represent the who's who of secret, dark-money groups that are pumping a lot of money into our elections," said Steve Spaulding, chief of strategy for Common Cause. "She's not exactly an ethics lawyer representing mom-and-pop nonprofits. . . . We're talking about the Koch brothers' nonprofits."

Vogel and attorneys working for her firm — based in rural Warrenton, 50 miles west of Washington — declined to be interviewed. Through a campaign spokesman, Vogel issued a brief statement that said attorney-

client privilege prevents her from discussing her work.

"As an ethics attorney, I hold myself and my firm to the highest ethical and moral standards possible and I don't settle for anything less," read the statement, which then sought to shift attention to the law practice of her Democratic opponent, Justin Fairfax, a former federal ­prosecutor-turned-corporate lawyer. "There is absolutely no basis to this story at all."

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Cleta Mitchell, a prominent GOP elections lawyer with Foley & Lardner in Washington and a longtime friend of Vogel's, said it's "outrageous" for anyone to question Vogel's integrity based on her legal specialty.

"What she does, what all of us in this field do, is we advise our clients how to exercise their First Amendment rights . . . without running afoul of the law," Mitchell said, noting that conservatives do not have a monopoly on dark money.

"The darkest of dark money is when unions take their members' dues and spend it on political activities about which the member actually either doesn't know and with which the member may not agree," she said. "AFP, Crossroads, any other advocacy group left or right . . . that's voluntary, after-tax dollars. . . . Compare that with the unions, where Joe Lunchbucket doesn't know where that money's going to be spent."

Vogel's firm has sometimes been accused by regulators and election officials of pushing the limits of election law.

That was the case in California in 2012, when mysterious donors poured $15 million into two California proposition battles not long before Election Day.

Some of the money was to oppose Proposition 30, which eventually passed and raised the California sales tax and income tax. The rest was to support Proposition 32, which failed and would have prohibited unions from using payroll deductions for political purposes.

The size of the donation raised eyebrows, as did the source: out-of-state nonprofits that had never been involved in California politics.

[California donor disclosure case exposes how nonprofits play in politics]

When California regulators finally unraveled it — on the eve of Election Day, after the state Supreme Court held an unprecedented Sunday session to order disclosure — the source of the $15 million turned out to be close to home: wealthy Californians, including the Fisher family that founded the Gap retail chain and San Francisco investor Charles Schwab, who had wanted their names kept under wraps.

Under federal election law, the names could be kept private. But California state law requires the disclosure of donors who sponsor ads within 60 days of an election. Rather than disclose, the money was shifted from one Koch brothers' nonprofit to another with help from Vogel's firm, said Ann Ravel, a former Federal Election Commission member who was then the state's chief elections watchdog as chair of the California Fair Political Practices Commission (FPPC).

"It's like if a restaurant gave money to all their employees to make donations to a political issue," Ravel said. "That's illegal. You have to give contributions in your own name. You cannot essentially launder it."

Those involved were not charged with any crime; they reached a civil settlement with the FPPC and state attorney general and were ordered to pay a record fine of $1 million. And the two California political committees that had received and spent the money were ordered to pay the state $15 million.

Vogel did not play any role in the California case, her campaign spokesman said.

But legal experts say that as managing partner of the 13-

lawyer firm, Vogel is ultimately responsible for its actions, much as a chief executive is responsible for the activities of a corporation.

Vogel's firm was at the center of controversy again last fall, right after Gov. Pat McCrory of North Carolina came up short in his reelection bid. HVJT was enlisted to help McCrory, a Republican, who was refusing to concede.

Within weeks, the firm filed protests against 600 voters across the state. It said some voters were dead and others had voted in two states or were felons who had not completed their sentences.

But the state and local elections officials eventually threw out the protests because they were riddled with mistakes — sometimes confusing legitimate voters with ineligible people with similar names, according a study by the nonpartisan Democracy North Carolina.

Voters saw their names appear in newspapers, as suspects in an alleged felony voter fraud conspiracy. Some had to defend themselves before they were cleared by local elections boards.

Pressly M. Millen, a North Carolina attorney for several voters who were falsely accused of voting illegally, said the protest was an attempt to delegitimize the election.

Stephen T. Smith, a prominent Raleigh, N.C., lawyer, filed a grievance with thestate bar against four lawyers from Vogel's firm, saying they had violated rules of professional conduct. Bar officials would neither confirm nor deny the existence of a pending complaint. Smith said he believes it remains pending.

In her brief statement to The Washington Post, Vogel said she was "never aware of any such complaint made against my firm."

The bar complaint is not against the firm per se but against the four lawyers, who did not respond to requests for comment. Vogel was not among the four. But the firm was recently added as a defendant in what could become a class-action lawsuit on behalf of all voters falsely accused of illegal voting. A judge will decide whether Vogel's firm should be part of the suit.

Chris West, a spokesman for the Vogel campaign, said she was unaware that her firm had been named in a lawsuit.

"Certainly no allegations even link Senator Vogel to any work in North Carolina, nor has any document been cited to name Senator Vogel," he said in a text message. "All work done in North Carolina by other lawyers in the firm was done under the supervision of North Carolina lawyers. There is no basis to this story at all and none of this has anything to do with Senator Vogel or the Lt. Governor's race in Virginia."

Vogel, 47, is a Shenandoah Valley native and the daughter of a longtime Republican donor, Holtzman Oil founder William B. Holtzman. He has donated $1.9 million to her campaigns and those of other Virginia Republicans over the past 10 years, including $611,000 toward Vogel's current bid.

[Republican Jill Vogel embraces the Trump agenda in her Virginia race]

Vogel was appointed chief counsel to the Republican National Committee in 2004, under her ticketmate Gillespie, who was then chairman.

After establishing her own firm, Vogel made "strategic hires" from the world of politics that helped fuel its rapid growth, Mitchell said.

Vogel's firm includes her husband, Alex Vogel, former chief counsel to then-Senate Majority Leader Bill Frist (R-Tenn.); Tom Josefiak, a former Federal Election Commission chairman and general counsel to President George W. Bush's 2004 campaign; and Jason Torchinsky, deputy general counsel for that campaign.

Along with super PAC American Crossroads, HVJT has represented its tax-exempt affiliate, Crossroads Grassroots Policy Strategies, which pioneered the use of nonprofits as dark-money political players. Known as 501(c)(4) groups, they are allowed to keep their contributors secret as long as they don't spend most of their money on politics.

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Vogel's ties to many of the super PACs and dark-money groups are a matter of public record, disclosed in Federal Election Commission and IRS filings. In addition to reporting payments to the firm, the organizations sometimes use HVJT's Warrenton address as their own and list HVJT lawyers as their treasurers or other officials.

Years ahead of Vogel's statewide campaign, one of her partners spoke to a reporter about the firm's work, which he described as helping clients with legitimate free-speech rights navigate a shifting legal landscape.

"The rules keep changing," Torchinsky told Bloomberg News in 2012, "which is part of the reason that people need law firms to figure out how to speak."