Obama camp claims $146.6 million in cash

The Obama campaign has $146.6 million in cash on hand at the start of June, according to newly-released filings with the Federal Election Commission.

The total includes the cash held by Obama for America, the Democratic National Committee, the Obama Victory Fund (a joint fundraising committee) and the Swing State Victory Fund.

One potential cause of concern for the Obama camp: Obama for America spent more money in May ($44.6 million) than it raised ($39.1 million).

The Obama camp announced earlier this monththat it raised a total of $60 million in May between its various committees. The Romney camp raised $76.8 million for the month.

Romney's cash on hand is not yet clear. His own campaign fund has just $17 million in cash on hand (compared to $109.7 million for Obama for America), but the Republican National Committee reported $61 million in cash on hand, and numbers for Romney's joint fundraising committee were not immediately available.

The Romney camp said that Wednesday was the biggest single fundraising day of the entire campaign, with between $6 million and $8 million raised.

On a conference call with reporters Wednesday, the Obama campaign argued that it would ultimately be outspent. They pointed to the outside groups freed up to spend unlimited amounts to influence the election by the Supreme Court.

"We are going to be the first incumbent outspent," a senior Obama campaign official said. The campaign estimates that Romney, the RNC, and all of the pro-Romney/GOP super PACs combined will spend $1.225B on ads this cycle. Another staffer said the outside groups are "one of the most significant challenges we face."

Democrats have lamented their significant disadvantage among outside group fundraising. Republican-linked groups like the Romney-supporting super PAC Restore Our Future, the Karl Rove-linked Crossroads groups, the Koch brothers-linked Americans for Prosperity, and the U.S. Chamber of Commerce have raised tens of millions so far this election cycle.

Democrat-supporting groups have lagged behind. Priorities USA Action, which supports the president, raised $4 million in May - it's best fundraising month ever - and says it is on track to raise more in June. Restore Our Future raised $5 million for the month.

Much of Priorities USA's new money was due to the emergence of three new million dollar donors supporting Mr. Obama. Texas trial lawyer Steve Mostyn is a well-known Democratic donor in Texas but his $1 million donation was his first to Priorities USA. Tennessee native Franklin Haney is a real estate developer who owns 15 million square feet of office space in the southeast and Washington, D.C. and is reportedly good friends with former Vice President Al Gore.  Haney also gave $1 million.

The third million dollar donor is South Florida philanthropist Barbara Stiefel. She has multiple foundations and has given generously to children's charities in Africa. One foundation affiliated with her family supports the atheist movement. 

In other super PAC news, the group supporting Newt Gingrich, Winning Our Future, refunded $5 million to billionaire casino magnate Sheldon Adelson's wife, Miriam, according to FEC filings. It was refunded to her on May 1, the day after Gingrich suspended his campaign.

CBS News investigative producer Laura Strickler contributed reporting to this article.