The shifting political tides in a coastal South Carolina congressional district are vividly apparent from the first look at last-minute big donations to Mark Sanford and Elizabeth Colbert Busch, rival candidates for the House seat left vacant when Republican Tim Scott was promoted to the U.S. Senate earlier this year.

Under federal law, any donations of $1,000 or more made during the final days before the May 7 election must be reported to the Federal Election Commission. Over the weekend, both campaigns filed their first reports, and they showed the late money breaking strongly in favor of Democrat Colbert Busch, a political rookie whose chances have suddenly improved on the heels of Sanford's latest stumbles.

The sister of comedian Stephen Colbert filed two reports with the FEC listing $33,000 in contributions. Her donors are a who's who of powerful Democrats and Democratic constituencies, including the leadership PAC of Rep. Bennie Thompson, D-Miss., his party's top-ranking member on the Homeland Security Committee ($1,000); former Georgia Gov. Roy Barnes ($2,600), and D.R.I.V.E., the political action committee of the Teamsters ($2,500).

In addition, VoteVets appears poised to become the latest outside spending group to enter the contest on Colbert's behalf with the ad seen above, which makes a clear reference to the sex scandal that engulfed Republican Sanford's closing term as South Carolina governor.

Update 3:47 p.m.: VoteVets Action Fund just sent us a press release about the ad.The group says the $30,000 buy will begin Tuesday and run through the end of the week on broadcast and cable stations.

Colbert Busch last week also benefitted from more than $300,000 in independent expenditures by the Democratic Congressional Campaign Committee and House Majority PAC. 

By contrast, prominent members of the Republican establishment went out of their way last week to distance themselves from Sanford, a former South Carolina governor who up until last week appeared poised to make a miracle comeback in a House district he once represented. Prior to the March primary election in the district, it was Sanford who was the beneficiary of all the late contributions, including many from established GOP political givers. 

That support may have dried up after news broke last week about Sanford facing court charges for trespassing at the home of his former wife, who also told reporters that one of her two sons had his first introduction to his father's Argentine mistress-turned-fiancée at Sanford's primary night victory party. Officials at the National Republican Congressional Committee told reporters they would not be helping Sanford and fellow South Carolina Republicans were just as notably unsupportive. 

Tellingly, Sanford reported just one late contribution over the weekend: $2,500 from the political action committee of Sen. John McCain, R-Ariz. McCain is a well known contrarian who often delights in thumbing his nose at party leaders. In this case, however, the contribution may be motivated by loyalty: Sanford chaired McCain's 2000 presidential campaign in South Carolina, a bitter fight that the senator lost to future President George W. Bush. 

Update: 4:11 p.m.: Sanford just filed another report with the FEC that includes a $5,000 contribution from the political action committee of Boeing. The airline manufacturer has a major facility in the congressional district that Sanford is vying to represent.

Another guage of how political smart money is evaluating the race: Colbert Busch has been the beneficiary of at least eight major fundraisers captured by Sunlight's Political Party Time. So far, we've seen none for Sanford, and The Hill reported that a Washington fundraiser for Sanford was cancelled after the revelation about his court date.

(Contributing: Louis Serino)