Financial disclosure reports released on Thursday offer a peek at the personal fortunes of lawmakers who could be potential running mates for Mitt Romney.  

Sens. Rob PortmanRobert (Rob) Jones PortmanSenate moving ahead with border bill, despite Trump 13 GOP senators ask administration to pause separation of immigrant families Lawmakers, businesses await guidance on tax law MORE (R-Ohio), Marco RubioMarco Antonio RubioPolitical figures pay tribute to Charles Krauthammer Senate moving ahead with border bill, despite Trump Hillicon Valley: New FTC chief eyes shake up of tech regulation | Lawmakers target Google, Huawei partnership | Microsoft employees voice anger over ICE contract MORE (R-Fla.), John ThuneJohn Randolph ThuneRepublicans agree — it’s only a matter of time for Scott Pruitt Senate moving ahead with border bill, despite Trump On The Money — Sponsored by Prudential — Senators hammers Ross on Trump tariffs | EU levies tariffs on US goods | Senate rejects Trump plan to claw back spending MORE (R-S.D.) and Rep. Paul RyanPaul Davis RyanPolitical figures pay tribute to Charles Krauthammer House approves five-year farm bill House postpones vote on compromise immigration bill MORE (R-Wis.) all released their yearly listing of assets and liabilities. Some of the VP contenders have lingering debts, while other are firmly ensconced in the millionaires’ club.

Portman's wealth climbed to at least $6.7 million in 2011, according to his financial disclosure form. That’s a 26 percent jump from 2010, when the former Office of Management and Budget Director reported $5.3 million for his minimum net worth. 

Portman’s liabilities dropped from at least $1 million in 2010 to at least $750,000 last year, which is partly responsible for the boost in his portfolio.

Combined with several hundreds of thousands of dollars in investment funds, Portman also has sizable holdings in real estate. He has a $1 million asset, for example, tied into an S corporation that has commercial rental property, buildings and vacant land in Cincinnati and Lebanon, Ohio, as well as in Erlanger, Ky.

Ryan’s worth is also in the seven figures. The House Budget Committee Chairman’s minimum net worth remained relatively the same from 2010 to 2011, dropping from $1.3 million to $1.2 million.

Among his assets, the Wisconsin Republican held at least $100,000 in gravel rights in Madill, Okla., as well as another $100,000 in a mining company in the same town. Ryan also reported one liability in 2011 — a mortgage on his personal residence in Janesville, Wis., for at least $250,000.

Under the STOCK Act, which passed earlier this year, lawmakers have to disclose mortgages on their personal residences for the first time. 

That might be why Rubio's minimum net worth decreased last year. His liabilities climbed to at least $550,000 in 2011, up from $200,000 in 2010.

Rubio reported a Chase home loan worth at least $250,000 and a U.S. Century Bank home equity loan valued at least $100,000 on his 2011 financial disclosure form; neither liability was on his 2010 report. He also has at least $100,000 in student loans with Sallie Mae.

Consequently, the Florida senator’s liabilities outweighed his assets in 2011, giving him a negative minimum net worth of negative $422,000.

Another vice presidential contender also might have found himself in the red because of the new requirement to disclose personal mortgages.

Sen. John Thune (R-S.D.) reported no liabilities in 2010. But Thune included two liabilities on his 2011 report — two refinanced mortgages that are worth least $100,000 each.

Thune's wealth declined from $170,000 in 2010 to negative $42,985 last year, according to financial disclosure reports. 

The reports do not give exact figures for lawmakers’ assets and liabilities but provide a value range for each. The Hill takes the bottom value of each item and subtracts the sum of a lawmaker’s liabilities from the sum of their assets to arrive at a conservative estimate for their net worth.

This story was updated at 6:28 p.m.

Rachel Leven contributed.