House Democratic leader Rep. Nancy Pelosi said on Thursday that the nuclear deal negotiated by the United States, Iran and Western powers "will have my strong support. I'm very optimistic about our ability to support the president" on the agreement, she told reporters at her weekly news conference, reports ABC News.

Holding a copy of the document detailing the deal that will dismantle much of Iran's nuclear infrastructure in return for sweeping sanctions relief, Pelosi praised President Barack Obama for his administration's role in negotiating the agreement.

"This was the product of tough, bold, clear-eyed leadership on the part of President Obama," she continued, reports The Huffington Post. "This agreement is precisely about intensifying our vigilance over every aspect of the Iranian nuclear program. We have no illusions about Iran."

The Obama administration has launched a full-court press to win over skeptical Democrats in Congress, and Pelosi's support is a key gain. The historic agreement would curb Tehran's nuclear program in exchange for billions of dollars in sanctions relief.

Under legislation passed in May, Congress has two months to review the finished deal, after which lawmakers will have the option to vote on a resolution of approval or disapproval, or to do nothing. To reject the deal, two-thirds of members in both chambers will need to vote against it in order to override a presidential veto. Obama has vowed to veto any legislation that tries to stop the implementation of the international agreement with Iran.

Vice President Joe Biden met with House Democrats on Wednesday to brief them on the deal. The vice president was returning to Capitol Hill on Thursday for a session with members of the Senate Foreign Relations Committee, reports the Associated Press, via US News & World Report.

Pelosi wouldn't go so far as to say she thinks her caucus would be able to sustain a veto. She said members are in the "education phase" right now, but added that the responses she is getting from House Democrats are "very positive."

"There is excitement about the fact that President Obama was able to keep P5+1, bring them to the table, and to sustain that engagement for a long period of time to produce an agreement is quite remarkable," Pelosi said.

In contrast with Pelosi's optimism, a number of Republicans in both chambers have criticized the deal.