Senate Intelligence Chairwoman Dianne Feinstein, D-Calif., said Monday that there is “no doubt” former CIA Director David H. Petraeus will have to testify before Congress on the terrorist attack on the U.S. consulate in Benghazi, Libya.

Feinstein told MSNBC that the intelligence community has refused to give her access to a trip report from Petraeus’ visit to Benghazi last month. Petraeus was scheduled to appear before the Senate and House Intelligence committees this week but instead shocked the Washington, D.C., establishment Nov. 9 by announcing he was resigning because of an extramarital affair.

“We have asked to see the trip report. One person tells me he has read it, and then we tried to get it and they tell me it hasn’t been done,” Feinstein said. “That’s unacceptable. We are entitled to this trip report. And if we have to go to the floor of the Senate on a subpoena, we will do just that.

“I have no doubt now that we will need to talk with David Petraeus,” she added. “And we will likely do that in closed session. But it will be done, one way or the other.”

That’s a change of tone from just a day earlier, when Feinstein said on Fox News that she wasn’t sure whether the committee would need to call Petraeus. Acting CIA Director Michael Morell is now slated to appear in Petraeus’ place for the closed briefings on Thursday.

“That’s up to the committee,” Feinstein said Sunday when asked by Fox whether her panel needed to hear from Petraeus. “I think we should have this first hearing, which is the way they wanted to set it up, and then the committee will make the decision.”

A number of congressional committees are conducting inquiries into the Sept. 11 Benghazi attack, which killed U.S. Ambassador J. Christopher Stevens and three other Americans. It has since been revealed that the brunt of the U.S. presence in the city, a hotbed of the revolution that overthrew longtime dictator Moammar Gadhafi located in the country’s east, comprised CIA operatives tracking loose weapons and conducting other intelligence operations.

Lawmakers have complained that the Obama administration has not adequately briefed them on the volatile security situation in the lead-up to the attack or on the confused explanation for the assault, which was orchestrated by Islamic militants, and the U.S. response.

In addition to the Intelligence panel briefings this week, the Senate Foreign Relations Committee has a closed briefing with State Department officials scheduled for Tuesday afternoon, and the Senate Homeland Security and Governmental Affairs Committee is getting briefed by the same group of officials on Wednesday. The State Department is also briefing House leaders and committee chairmen on Friday.

Feinstein said Monday that she would consider a proposal to create a select committee to conduct Congress’ investigation, an idea first floated by GOP Sens. John McCain of Arizona, Lindsey Graham of South Carolina and Kelly Ayotte of New Hampshire. The trio sent a letter to Senate Majority Leader Harry Reid, D-Nev., and Minority Leader Mitch McConnell, R-Ky., on Nov. 3 suggesting they create such a body.

“I’d certainly be open to the proposal,” Feinstein said. “You don’t want to make it so big that it’s a problem, but on the other hand, this has to be bipartisan and it should be bicameral, I would think. So I’m open to the suggestion.”

Reid’s office did not respond to request for comment on the idea on Monday.