Indiana Treasurer Richard Mourdock put an additional $100,000 of his own money into his primary bid against Sen. Dick Lugar, the insurgent Republican’s campaign confirmed.

Despite his influx of personal cash, Mourdock’s campaign bank account remains a fraction of Lugar’s war chest four months before the May 8 primary.

Mourdock is waging a spirited bid against Lugar, but his campaign has struggled, mostly because of lackluster fundraising.

On Friday, Mourdock reported raising $386,000 in the fourth quarter, ending December with $362,000 in the bank. This is the second time he’s put his own money into the campaign, following up on another $100,000 donation in the third quarter.

Lugar raised $750,000 in the fourth quarter and kicked off the election year with $4 million in cash on hand.