Democrat Matthew Frumin’s campaign war chest is nearly twice as large as his nearest rival’s in next month’s D.C. Council at-large race, but Republican Patrick Mara has stepped up his fundraising over the past six weeks, according to campaign finance reports released Tuesday.

The reports come six weeks before the April 23 election, when voters will select a replacement from a field of seven candidates to fill out the term of the citywide seat once held by D.C. Council Chairman Phil Mendelson (D).

After a slow fundraising start, Mara reported raising $55,000 from Jan. 30 through Monday. Mara, who has $53,000 in the bank, received a boost from executives in the parking garage and construction businesses as well as local and national GOP activists.

But Mara, the only Republican in the race, returned a $1,000 contribution Tuesday after questions were raised about the donor. The contribution came from Freedom’s Defense Fund, which supports “conservative, pro-freedom candidates against the radical left and elitist mainstream media,” according to its Web site.

Among the candidates the group says it has supported is Rep. Trent Franks (R-Ariz.), who has proposed strict limits on abortion in the District.

Elissa Silverman, one of Mara’s Democratic opponents, said the donation was “an insult to the voters of the District.”

The group vows “to stop Washington D.C. from achieving statehood — resulting in two more liberal members in the U.S. Senate,” according to its Web site.

Mara said he planned to return the donation even before Silverman’s statement. “We don’t Google the name of every person or organization that supports our campaign,” Mara said. “We’ve received hundreds of donations.”

Among the Democrats in the race, D.C. Council member Anita Bonds has raised about $47,000 since January, according to campaign staffers. Bonds, appointed by the D.C. Democratic State Committee to fill the seat pending the election, has $45,000 in the bank, they said.

Bonds is running nearly even with Silverman, a former reporter who is on leave from the D.C. Fiscal Policy Institute. Silverman reported $47,000 in the bank after raising $25,000 since late January.

But Frumin continues to crush his rivals, bringing in an additional $46,000 over the period, including a second $10,000 personal loan to his campaign. The former Clinton administration official has raised a total of $123,000 and has $97,000 in the bank.

Meanwhile, former council member Michael A. Brown, who was ousted in November after one term, raised $31,000 during the period. A former independent who is running as Democrat, Brown has $28,000 on hand.

Another Democrat, lawyer Paul Zukerberg, has $15,000 in the bank, and records show that Perry Redd, a Statehood Green Party candidate, reported $1,500 in the bank.