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Remy de la Mauviniere, Pool, Associated Press
U.S. Secretary of State John Kerry, left, is greeted by French foreign minister Laurent Fabius prior to their meeting at the foreign ministry in Paris Thursday, Nov. 20, 2014. U.S. Secretary of State John Kerry is in Paris for talks with the French and Saudi foreign ministers as part of a last-minute push to secure a nuclear deal with Iran.

PARIS — U.S. Secretary of State John Kerry will travel to Vienna later Thursday to join high-level nuclear negotiations with Iran as a deadline for an agreement fast approaches.

State Department spokeswoman Jen Psaki said Kerry would be going to the Austrian capital from Paris to "check in" on the talks. It was not yet determined how long he would stay in Vienna, leaving open the possibility that he might not remain until Monday's deadline for a deal. Kerry is to meet with the U.S. negotiating team in Vienna late Thursday before scheduling meetings with other participants.

"We do want to get an agreement, but not just any agreement," Kerry said Thursday after meeting in Paris with the Saudi and French foreign ministers. "We hope that the gaps that exist — and they do exist — can be closed. We hope we can define the finish line."

French Foreign Minister Laurent Fabius, standing next to Kerry, said important points of difference remain.

Kerry had been expected to join the Vienna negotiations, but the timing of his arrival at the talks had been uncertain until shortly after he arrived in Paris after two days of similar meetings in London with his British and Omani counterparts. Kerry was to hold a news conference in Paris before departing for Vienna.

With Monday's deadline for a deal looming, Kerry has embarked on a frenzy of high-stakes diplomacy in a last-minute push to secure an agreement — or at least prevent the process from collapsing after talks were already extended once.

Senior negotiators in Vienna have spent three days racing against the clock to forge a pact over the next five days that would prevent Iran from reaching the capability to produce atomic weapons.

Despite Kerry's efforts, though, signs increasingly pointed to the Nov. 24 deadline passing without a deal and the negotiations being extended a second time.

In London on Tuesday and Wednesday, Kerry met with Foreign Minister Yusuf bin Alawi of Oman, a key bridge between Washington and Tehran, a senior U.S. official said.

Kerry's meetings Wednesday with Fabius and Saudi Foreign Minister Saud al-Faisal are considered critical because French objections last year delayed the adoption of an interim agreement by several weeks, and Saudi Arabia remains deeply concerned about the potential for its archrival Iran to win concessions from the West.

In Washington on Wednesday, President Barack Obama's nominee to be Kerry's deputy at the State Department said he believed it would be difficult to meet the deadline.

"It's not impossible," said Tony Blinken, currently Obama's deputy national security adviser. "It depends entirely on whether Iran is willing to take steps it must take to convince us, to convince our partners that its program would be for entirely peaceful purposes. As we speak, we're not there."

The Obama administration also is trying to satisfy the concerns of lawmakers, Republican and Democratic, at home.

Republican senators sent a letter to the White House on Wednesday urging the administration against trying to circumvent Congress in any deal with Iran. "Unless the White House genuinely engages with Congress, we see no way that any agreement consisting of your administration's current proposals to Iran will endure," said the letter, which was signed by all 45 Senate Republicans.

Associated Press writers Bradley Klapper and Lara Jakes in Washington and Tia Goldenberg in Jerusalem contributed to this report.