By Chris Frates
CNN Investigative Correspondent
WASHINGTON (CNN) -- Just days after dismissing two top advisers for their roles in the George Washington Bridge scandal, New Jersey Gov. Chris Christie is facing questions over the use of Superstorm Sandy relief funds.
CNN has learned that federal officials are investigating whether Christie improperly used those relief funds to produce tourism ads that starred him and his family.
The news couldn't come at a worse time for the scandal-plagued Republican, who is facing two probes into whether his staff tied up traffic near the country's busiest bridge to punish a Democratic mayor who refused to endorse his successful re-election bid.
If the Sandy inquiry finds any wrongdoing, it could prove even more damaging to Christie's national ambitions. His performance during and after the superstorm has been widely praised and is a fundamental part of his straight-shooting political brand.
In the new probe, federal auditors will examine New Jersey's use of $25 million in Sandy relief funds for a marketing campaign to promote tourism at the Jersey Shore after Sandy decimated the state's coastline in late 2012, New Jersey Democratic Rep. Frank Pallone told CNN
In an August letter, Pallone asked the Department of Housing and Urban Development inspector general to look into how Christie chose to spend the marketing money approved by the department.
Neither the governor's office nor the inspector general's office has replied to CNN's request for comment on the investigation.
Pallone wrote that he was concerned about the bidding process for the firm awarded the marketing plan; the winning firm is charging the state about $2 million more than the next lowest bidder. The winning $4.7 million bid featured Christie and his family in the advertisements while the losing $2.5 million proposal did not feature the Christies.
On Sunday, Pallone told CNN that the inspector general conducted a preliminary review of the spending and concluded that there was enough evidence to launch a full-scale investigation into the state's use of federal funds. The audit will take several months, and the findings will be issued in an official report, he said.
Pallone, a 27-year veteran of the House and vocal Christie critic, said this is not about politics.
"This was money that could have directly been used for Sandy recovery. And, as you know, many of my constituents still haven't gotten the money that is owed them to rebuild their homes or raise their homes or to help," he told CNN.
Democrats slammed Christie over the summer for starring in taxpayer-funded ads as he was running for re-election in November, arguing it gave him an unfair advantage. Christie aides said at the time that the winning bid provided more value.
Last week, Christie dismissed two top aides for their involvement in closing down access lanes to the George Washington Bridge last year, a move that tied up traffic for four days. A New Jersey State Assembly committee is investigating whether the aides ordered the lane closures as political retribution, and the U.S. Attorney in New Jersey has opened a probe into the matter.
For his part, Christie has said he didn't know about the scheme and was "embarrassed and humiliated" by it. Democrats, both in New Jersey and nationally, have jumped on the scandal, saying it finally gives the nation an opportunity to see what they've known for years, that Christie is a bully who governs by fear.
But as bad as the bridge scandal is for Christie, if investigators find he improperly spent Sandy funds, it could get far worse, tarnishing the signature achievement that has made him a serious contender for the White House.
CNN's Scott Bronstein contributed to this report.
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