Some U.S senators have more to lose than others if Congress’ upper chamber is unable to pass a budget by April 15.

According to a provision included in the U.S. House of Representatives’ "No Budget, No Pay" debt ceiling bill, members of Congress will have their pay withheld if it does not pass a 2014 budget resolution. That’s easy for the House, which already passed Paul Ryan’s “Road to Prosperity” budget and is currently working on an updated version of the bill. But the Senate has, notably, been unable to agree on a budget in four years.

Under the House bill, pay would be withheld until the 113th Congress ends on Jan. 3, 2015.

Most members of the Senate -- often referred to as the “millionaires’ club" -- may not sweat the loss of their $174,000 annual salary. But the move could jeopardize the livelihood of a small group of senators, who have a net worth ranging in the thousands rather than millions.

Granted, the setback will only be temporary. If Congress has not reached a resolution on the budget by the April 15 deadline, their paychecks will be deposited into an escrow account they will eventually be able to access -- even if it isn’t until 2015.

Below are the five poorest U.S. senators, along with their personal net worth, as reported in 2011 financial disclosure forms. Because lawmakers are permitted to report value ranges, rather than exact figures, the Center for Responsive Politics has calculated a simple average to determine each senator’s estimated wealth.

Sen. Marco Rubio, R-Fla., -$45,494

U.S. Sen Marco Rubio, R-Fla., scored a huge political victory on Thursday: The 2013 immigration reform bill cleared the upper chamber with a bipartisan 68-32 vote, just hours after he supported it in a rousing speech on the Senate floor. Reuters

That's right: It's a minus sign. Surprisingly, the GOP’s newest rising star may also be the poorest member of the Senate. Rubio, who has anywhere between $127,000 to $482,000 in assets, also has multiple home mortgages, sending his net worth into the red. The Florida lawmaker also has up to $250,000 in student loan debt.

Sen. Debbie Ann Stabenow, D-Mich., $0

Sen. Debbie Stabenow

Stabenow did not report any assets in 2011, according to the center. However, the Michigan senator reported liabilities between $600,000 to $1,250,000, including refinanced mortgages and a home equity line of credit.

Sen. Christopher S. Murphy, D-Conn., $7,502

Sen. Christopher Murphy Reuters

While Murphy has a modest net worth compared to most in Congress, he managed to defeat WWE chairwoman Linda McMahon, who injected $48 million of her own money into a senate run, during the 2012 election.

Murphy has between $30,000 to $100,000 worth of student loan debt with Sallie Mae.

Sen. Mark Kirk, R-Ill., $17,501

Sen. Mark Kirk

Kirk joined Congress’ upper chamber after winning a special election to fill the seat vacated by then-Sen. Barack Obama. Kirk has at least $515,000 in liabilities primarily stemming from outstanding mortgage payments.

Sen. Jeff Flake, R-Ariz., $32,500

Sen. Jeff Flake Office of Congressman Jeff Flake

Although Flake has up to $50,000 in Apple stock and a pricey apartment in Provo, Utah, his estimated wealth was severely downgraded by two mortgage liabilities. Together, those liabilities range between $750,002 and $1.5 million.