Democrat Elizabeth Colbert Busch raised more than twice the amount that Republican Mark Sanford did in the most recent reporting period -- possibly a sign that allegations by Sanford's ex-wife damaged his fundraising prowess.
Sanford still has more cash on hand heading into the final days of the race, though.
Colbert Busch and Sanford face each other in a May 7 special election to fill the 1st Congressional District seat vacated by Sen. Tim Scott, a Republican.
The numbers from the most recent campaign filings show Colbert Busch is getting strong support from national Democratic political action committees and groups. About $96,000 of the more than $874,000 she raised this period came from political action committees.
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Those include donations from unions, such as the Sheet Metal Workers' International Association and the United Transportation Union. Midwest Values PAC, a progressive group started by Minnesota Sen. Al Franken, a former writer and performer for "Saturday Night Live," also donated to her campaign.
Sanford has criticized Colbert Busch for her ties to national groups that he says are trying to "buy the race" with TV ads and mailers.
On Friday, Colbert Busch's campaign instead stressed her grassroots support, noting that more than two-thirds of donors live in South Carolina -- with more than 10,000 donors giving an average contribution of $63.
Overall, Colbert Busch raised more than $874,000 between March 14 and April 17 compared to Sanford's $375,000, according to new financial filings with the Federal Election Commission that track candidates fundraising and spending.
Sanford has more than $284,000 cash on hand, compared to just more than $254,000 for Colbert Bush.
Most of Sanford's donations were from South Carolinians and a handful from supporters in New York, Florida, Virginia and Georgia.
On Friday, Joel Sawyer, Sanford's spokesman, said the former governor remains competitive in fundraising despite going up against left-leaning groups backing his rival.
Unlike previous filing periods, Sanford has begun accepting donations from political action committees, receiving $12,500 in all from them.
They include the Washington, D.C.-based Club for Growth PAC, a fiscal-conservative group; Spartanburg-based payday lender, Advance America Cash; and the PACs of Arizona Republican Rep. Matt Salmon and Texas Republican Rep. Ron Paul, a former presidential contender.
Follow reporter Gina Smith at twitter.com/GinaNSmith.