The National Commission on Terrorist Attacks Upon the United States will send a bipartisan delegation to Capitol Hill today to brief Democratic Senators on its investigation and try to allay fears that the panel is engaging in partisan politics.

Vice Chairman Lee Hamilton and commission member John Lehman will meet with Democrats to discuss, among other subjects, how the commission plans to move forward as it prepares its report about the Sept. 11, 2001, terrorist attacks on the United States.

“What they want to do is go back to the Congress and tell them where they are, what is the schedule of events, and what they can expect to be unfolding in the next couple of months,” said Al Felzenberg, a spokesman for the commission, which is widely referred to as the 9/11 Commission.

Felzenberg added that the meeting would offer Senators an opportunity to “ask their questions” and for the commission members to “listen to their concerns — as they begin weighing policy recommendations.”

Today’s meeting was slated to be a joint meeting with the Democratic Policy Committee and the Republican Policy Committee. That would have made it a rare bipartisan gathering of the two political parties’ legislative arms. But a scheduling conflict forced Republicans to back out, and officials say they will schedule a separate briefing in the future.

The commission is seeking to keep an open line of communication with Capitol Hill at a time when some Republican Members of Congress have publicly questioned why Commissioner Jamie Gorelick — a Justice Department official in the Clinton administration — is a member of the panel.

At least two Republicans have called on Gorelick to resign her post, arguing that her current commission colleagues should be questioning the former Justice Department official about her own role in instituting policies that made it harder for federal agencies to share intelligence. Additional Senators and House Members have called on Gorelick to testify about her involvement in reinforcing an intelligence-sharing “wall.”

Commission Chairman Tom Kean, the former Republican governor of New Jersey, plus the eight other commission members have stood by Gorelick.

On Gorelick’s status, Felzenberg said, “there is no light between the chair and the vice chair and between the Republicans and Democrats on the commission.”

Despite such assurances, some Republicans said they remain concerned that the panel is becoming too partisan.

“Based on the public hearings, I am concerned that some of the commissioners seem to have adopted a very partisan approach, and I think that is unfortunate,” said Governmental Affairs Chairman Susan Collins (R-Maine). “This commission needs to be above politics. It needs to put partisan agendas aside.”

Sen. Trent Lott (R-Miss.) added that his concern is that the commissioners “got their profile too high” by speaking about their investigation to the news media.

So far, Kean and Hamilton, a former Democratic Representative from Indiana, have met with House GOP leaders as well as House Minority Leader Nancy Pelosi (D-Calif.). A Pelosi spokesman said another meeting between commissioners and the House Democratic Caucus could occur as early as next week.

A meeting with Senate Republicans is in the cards, said RPC Chairman Jon Kyl (Ariz.). “The DPC is going to meet with them and we are going to try and find another time,” Kyl said. “We had another lunch on Thursday and we are going to have to do it another occasion.”

DPC Chairman Byron Dorgan (N.D.) said Democrats are looking forward to having a “dialogue about what the commission is doing.”

Sen. Jay Rockefeller (D-W.Va.), the ranking member on the Intelligence Committee — which is engaged in its own investigation of the 9/11 attacks — said that he too welcomes the commissioners’ willingness to discuss their findings with Congress.

“The more people talk about it, the better it will be,” Rockefeller said.

The commission is required by law to complete its work by July 26, but Felzenberg said that the panel’s goal is “to get it out earlier.”

Sen. John McCain (R-Ariz.) said the criticism of the commission is premature and people should wait until the report is finished.

“I think the key will be whether there is a unanimous report signed by everybody,” McCain said.