The campaign of Tom Wiens (R), a former state Senator, says the candidate loaned his U.S. Senate campaign $540,000 in late 2009. That accounted for early three-fourths of his total receipts of $728,000.

Wiens is seeking the Republican nomination for the seat of Democratic Sen. Michael Bennet.

The GOP primary also includes former Lt. Gov. Jane Norton, whose campaign has received financial assistance from party heavyweights in Washington, D.C., and Colorado.

The other major Republican candidate is Ken Buck, a county prosecutor.

Bennet faces opposition in the Democratic primary from Andrew Romanoff, a former state Speaker.