Two top aides to Rep. John Doolittle (R-Calif.) have been subpoenaed for grand jury testimony in U.S. District Court for the District of Columbia as part of the Justice Department’s ongoing probe of the California lawmaker’s ties to convicted lobbyist Jack Abramoff.

Doolittle’s chief of staff, Ron Rogers, and his deputy chief of staff, Dan Blankenburg, notified the House on Tuesday that they had received the grand jury summons, as is required under House rules. A statement released by the nine-term Californian confirmed that the two aides will testify this week, in hopes of bringing a swift end to the ongoing probe.

“I think everyone can agree that this issue needs closure,” Doolittle said. “Three years seems like more than adequate time to determine the facts. I look forward to the truth finally being established and hope that we may have a resolution soon.”

Doolittle and his wife, Julie, have been under federal investigation in connection with the Abramoff influence-peddling scandal that last year brought down former Rep. Bob Ney (R-Ohio). In April, the FBI raided the Doolittle’s Oakton, Va., home.

Both Doolittles had close ties to Abramoff. Julie Doolittle ran a GOP fundraising firm and did work for Abramoff. Kevin Ring, a former senior Doolittle aide, left the office to become one of Abramoff’s top associates at a lobbying firm.

The Justice Department has sought to talk with as many as a half-dozen former Doolittle aides. However, Blankenburg and Rogers are the first current aides publicly known to have been subpoenaed. Both men joined Doolittle’s staff after the federal investigation began.

Earlier this year Doolittle agreed to relinquish his seat on the Appropriations Committee until the matter is resolved.

Although Doolittle’s statement Tuesday noted that the investigation has not deterred him from his official duties, there is mounting evidence that the Congressman’s political support is eroding further back home.

Just last week, state Assemblyman Ted Gaines (R) became the first state legislator to begin publicly exploring a challenge to Doolittle in a primary next year. Gaines said he has formed a committee to look at running and made clear that Doolittle’s ethical troubles are the reason he is doing so.

Doolittle, who came close to being defeated for re-election in 2006, already had drawn two lesser-known primary opponents for 2008.

At a meeting with reporters Tuesday afternoon, House GOP Conference Chairman Adam Putnam (Fla.) acknowledged that ethical issues continue to cast a shadow over Capitol Hill, but he insisted that both parties were to blame.

“There is a cloud over this Congress,” Putnam said. “It’s reflected in an 18 percent approval rating. It’s a bipartisan cloud.”