Kansas Sen. Pat Roberts has maintained his big fundraising advantage over tea party challenger Milton Wolf in their Republican primary race.

Roberts’ re-election campaign disclosed Tuesday it had raised nearly $797,000 in cash contributions from April through June. Wolf’s campaign reported raising almost $341,000.

The three-term incumbent began the quarter with nearly $2.25 million in cash on hand, and his campaign spent more than $1.05 million during the period. Wolf spent a little less than $340,000.

Summaries of their campaigns’ most recent reports for federal regulators show Roberts had more than $2.05 million in cash on hand at the end of June, compared with $280,000 for Wolf.

Roberts’ re-election campaign has spent more than $2.13 million since the beginning of last year. Wolf has spent $649,000 total.