President Obama did it. So did Secretary of State John Kerry, Treasury Secretary Jacob Lew, Defense Secretary Chuck Hagel and Attorney General Eric Holder. Some members of Congress have offered to do it, too.

But, setting up an awkward dynamic in the White House, there’s one high-profile Cabinet member who has not yet publicly pledged to return some of his government salary: Vice President Joe Biden. You would think that someone who has hinted he wants to run for president in 2016 would have a photo-op handing over the money.

One possible explanation is Biden’s net worth, which is on the modest side compared to the president and other Cabinet members. The Center for Responsive Politics calculates the vice president’s net worth at between $39,000 and $800,000 while the president’s ranges from nearly $3 million to just over $ 8 million. Kerry's net worth is estimated at between nearly $200 million and $300 million; Hagel's ranges from $2 million to $11 million, and Lew's is anywhere from $750,000 to to almost $2 million. 

“It is a more difficult calculus for members who are not as wealthy,” said one long-time senior Democratic Senate aide, who spoke on the condition of anonymity so he could be candid.

Of course being a millionaire probably makes it a little easier to pledge to return a percentage of your salary to the federal government to stand in solidarity with federal employees who’ve taken pay cuts because of budget cuts due to sequestration.

But because Obama will give $20,000 of his $400,000 salary back to the Treasury to share the pain of $85 billion in budget cuts that went into effect last month, the pressure on Biden to do the same is higher.

“Ultimately here, PR rules the day,” said the long-time aide. “It's a way they can illustrate the common touch.”

The vice president’s office did not reply to requests for comment.

Far from super-wealthy, Biden is not the only Cabinet member who hasn’t publicly said he’d give back part of his salary. Health and Human Services Secretary Kathleen Sebelius is not planning to give back part of her pay, though, her estimated net worth is as high as $5 million, The New York Times reported.

Still, Homeland Security Secretary Janet Napolitano whose net worth is in line with Biden’s at $93,000 to $700,000, said she’d give back 5 percent, according to the Times.

The administration is navigating rocky political waters with sequestration. Before the cuts took effect, the president argued that such a “meat-clever approach” would deliver a serious blow to the economy. But since the cuts went into effect the economy has not—yet, anyway—stumbled as badly as the president suggested. Now, Obama and the Cabinet are very publicly returning part of their salaries, a move that simultaneously suggests solidarity but also reminds voters, many of whom can’t afford to spare a dime, that their political leaders have tens of thousands to spare.

“If you’re a member of Congress, surely the notion of lead by example should not just be a slogan,” said Delegate Eleanor Holmes Norton of the District of Columbia, according to the Times.

Biden, who earns $230,700 annually as vice president, has already made some public gestures because of the cuts. In February he said he would again take Amtrak back to Delaware, just he did for three-plus decades while he was in the Senate.

“Look guys, I’ve got to take the train now,” Biden said at the time, according to the News Journal. “It’s cheaper than flying.”