Sen. Elizabeth Warren (D., Mass.) appeared flustered when a reporter asked if her ethics plan would bar her potential vice president's child from serving on the board of a foreign company.

The Warren campaign singled out fossil fuel companies that "spend freely on influence peddling" when she debuted an ethics policy intended to "end Washington corruption" on Sept. 16. But she fumbled with an answer when asked about whether the policy would apply to her vice president—a hypothetical scenario alluding to Hunter Biden's lucrative appointment to the board of a Ukrainian gas company while Joe Biden served in the Obama administration.

"No," Warren said, before haltingly adding, "I don't—I don't know. I mean, I’d have to go back and look at the details on the plan."

As the reporter followed up as to whether it would be a problem, Warren repeated she'd have to go back and look.

FLAG: Senator Elizabeth Warren appears uncharacteristically flustered when asked if her ethics plan would allow her Vice President's son to serve on the board of a foreign company: "No," she said. "I don't know. I mean I’d have to go back and look at the details." #nhpolitics pic.twitter.com/EksLlMEsew — Nicole Sganga (@NicoleSganga) September 25, 2019

Warren appeared uncomfortable at the idea of dinging Biden, the frontrunner in the 2020 Democratic presidential primary. The Massachusetts senator has conspicuously avoided attacking fellow Democrats as she's risen in the polls, becoming one of the top contenders for the party's nomination.

A Warren spokesman later said nothing in her plan would "prevent any children of a VP from serving on a company's board."

A Warren campaign spox on whether, under a Warren administration, her VP’s child could serve on the board of a foreign company: "The [ethics] bill doesn’t prevent any children of a VP from serving on a company’s board." — Annie Linskey (@AnnieLinskey) September 26, 2019

Warren's campaign has centered around the theme of battling a rigged political system that favors the wealthy and well-connected. In addition to targeting oil and gas companies, her plan to end Washington corruption calls for a ban on foreign lobbying.

"My plan categorically bans the practice of private lobbying for foreign governments, foreign individuals, and foreign companies," she wrote. "No more K Street influence-peddlers looking out for the interests of China, Russia, or Saudi Arabia."

Hunter Biden joined the board of Burisma in 2014 at a salary of $50,000 a month, leading to accusations that his hire was an attempt to influence his father, who oversaw Ukraine policy for the White House. Former Obama administration officials told the New Yorker the role Biden's son had at Burisma did not influence the vice president, but they called the appointment inappropriate.

President Donald Trump asked Ukrainian president Volodymyr Zelensky during a phone call in July to "look into" the Biden family in connection to the firing of a Ukrainian prosecutor. The conversation is now the subject of an impeachment inquiry conducted by House Democrats.

UPDATED: Thursday, 9:36 A.M.: This article was updated with a comment from a Warren spokesman.