WASHINGTON — Presumptive presidential candidate Fred Thompson on Tuesday will report raising roughly $3 million in one month for his all-but-certain White House bid, Republican officials said.

The figure will include money collected in June only, as the Internal Revenue Service requires. Dollars raised in July, during which Thompson has held several large fund-raising events, won't be disclosed.

Several Republicans with knowledge of Thompson's fundraising confirmed the first-month total on the condition of anonymity because he has not yet made the figure public. A Thompson spokeswoman, Linda Rozett, declined to comment.

The amount Thompson raised for his committee to "test the waters" of a presidential bid lags the original $5 million goal backers set for June, the first month in which he set out to raise money.

Thompson did, however, collect more than several other Republicans did in their initial fundraising months as prospective candidates. Still, Thompson's take doesn't even compare to the stunning $6.5 million haul that Mitt Romney collected on a single day in January as he was exploring a bid.

Joe Rodgers, a former finance chairman for the Republican National Committee and President Reagan's 1984 re-election campaign, said Thompson's status as a non-candidate has hurt his ability to raise money.

"It probably is a disadvantage because people that don't know Fred really don't know whether he's going to run," Rodgers said.

Rodgers, who co-hosted one of Thompson's first fund raisers in Nashville, said several potential donors told him they were willing to give money to Thompson once he officially declares his candidacy.

An actor and former Tennessee senator, Thompson filed papers with the state of Tennessee on June 4 to establish the "Friends of Fred Thompson, Inc." committee to "test the waters" of a presidential bid.

That allowed him to explore a candidacy without having to disclose to the Federal Election Commission how much he was raising and spending unless — or until — he becomes a declared candidate. But the IRS requires such entities to file reports.

Thompson's first such filing comes a week after the presumptive campaign went through a staff shake-up with the departure of its would-be campaign manager and several other aides.

Although Thompson has refused to say definitively that he's a candidate for president, he has operated as an unofficial one for two months, hiring staff, opening headquarters and holding fundraisers. He had been expected to enter the race in the summer but the timeline has been pushed back until September at the earliest.