U.S. Sen. Richard Lugar's tea-party backed challenger slightly outraised the long-term senator in their latest fundraising effort as the Republican primary draws close.

Indiana Treasurer Richard Mourdock reports he raised more than $875,000 through the first three months of the year and has $430,000 in the bank. Lugar's campaign said Thursday they raised $820,000 in the same time span and have more than $2.5 million in the bank.

At the start of the year Lugar held a 10-1 cash advantage over Mourdock. Likewise he has outspent Mourdock roughly 5-1 in campaign advertising. However deep-pocketed groups like the Club For Growth have jumped in the campaign and begun spending heavily on Mourdock's behalf.

A spokeswoman for Democratic U.S. Rep. Joe Donnelly said his numbers would not be available until Friday.