The Miami Herald reported the news Friday.
The figure tracks with the results of a recent Democratic poll, which showed Rivera trailing Garcia by 9 points.
GOP leaders had heralded Rivera as a rising star in the party when he arrived on Capitol Hill in 2011, but the charges surrounding his finances – both public and private – have dogged his tenure and threatened his political future.
Both the FBI and the IRS are currently conducting criminal investigations into allegations that he failed to report income on his tax returns. He's also been tied to an ongoing federal probe into a possible shadow campaign he may have conducted for Garcia's political rival during the Democratic primary race.
Rivera is hardly backing down, and his campaign continues to insist he'll keep his seat. Indeed, an internal poll released mid-month put him ahead of Garcia by 6 percentage points.
The New York Times labels the contest a toss-up.