MADISON, Wis. — Republican U.S. Senate candidate Kevin Nicholson says his campaign raised more than $1 million in the first three months of the year.

That is up from the $800,000 he raised in the last three months of 2017.

Nicholson's Republican challenger, state Sen. Leah Vukmir (VOOK'-meer), has not reported how much she raised over the period.

Nicholson and Vukmir face each other in the Aug. 14 primary. The winner will take on Democratic Sen. Tammy Baldwin in November.

Nicholson's campaign said Monday he had more than $800,000 cash on hand. He has raised more than $2.3 million since launching his campaign in July.

The Center for Responsive Politics says outside groups have already spent nearly $3.1 million against Baldwin and a whopping $4.8 million in support of Nicholson, with another $909,000 for Vukmir.