Cruz’s move tightens his vise grip on Biden’s diplomatic nominations during a time when the Iran nuclear deal is falling apart, tensions with China are ramping up, refugees want out of Afghanistan and sensitive climate change negotiations are coming to a head.

At the same time, Cruz is allowing other largely non-controversial State Department nominees to sail through without additional hurdles. The Senate Foreign Relations Committee, of which Cruz is a member, advanced dozens of nominations later Tuesday, including ambassadorships for former Sens. Jeff Flake (R-Ariz.) and Tom Udall (D-N.M.), as well as Cindy McCain and Julianne Smith, Biden’s pick to represent the U.S. at NATO headquarters.

Leaf’s nomination is the only one that Cruz held up during Tuesday’s markup; the rest were approved and sent to the Senate floor for final consideration.

But in a brief interview on Tuesday afternoon, Cruz told POLITICO that he’s leaving open the possibility of delaying Senate floor action on any of the nominees that the committee approved on Tuesday — not just Leaf’s.

“Going to the floor is a different question,” Cruz said.

Cruz’s hold on Leaf’s nomination — including his threat to slow-walk other nominees on the Senate floor — will force the administration to either explain its Middle East policy more fully, put pressure on Senate Majority Leader Chuck Schumer to spend precious floor time blowing past the hold, or pull her nomination altogether.

Leaf didn’t respond to a request for comment. Democrats slammed Cruz for the hold, accusing him of focusing on political theater at the expense of U.S. national security.

“Senator Cruz’s objection to Barbara Leaf has NOTHING to do with her qualifications,” Sen. Chris Murphy (D-Conn.), a Foreign Relations Committee member, wrote on Twitter. “It’s just more political grandstanding that leaves America vulnerable without a top diplomat in the Middle East.”

Tuesday’s move also opens a new front in Cruz’s policy fights with Biden.

The Texas senator’s holds on diplomatic and national-security nominees began as a protest against the administration’s decision to waive mandatory sanctions on the nearly completed Nord Stream 2 pipeline from Russia to Germany. Cruz and others from both parties believe that was a strategic blunder, as it will give Moscow more influence in Europe.

But now, the Texan is taking on the administration’s handling of its Middle East policy. Cruz is a longtime critic of the Iran deal and would prefer the U.S. remain out of the pact, while he also remains a supporter of the Donald Trump-negotiated Abraham Accords between Israel and Morocco, Sudan, Bahrain and the United Arab Emirates.

It’s expected that Cruz will now bring up his misgivings with Biden’s Middle East policy during Foreign Relations Committee meetings this week, escalating already high tensions between the lawmaker and the administration.

In vetting Leaf’s nomination, Cruz asked her to detail any “arrangements, deals, or agreements that are being contemplated by the Biden administration to reduce pressure on Iran” instead of a return to the 2015 nuclear deal. “There have been no such arrangements, deals, or agreements contemplated to reduce pressure on Iran,” Leaf responded.

“That testimony is false,” reads a two-pager Cruz’s team attached to the email. In the footnotes, Cruz’s team cited two Reuters stories reporting the U.S. considered taking small steps with Iran as a confidence-building scheme, and another about American officials pondering a “less for less” alternative, which would require fewer restrictions on Iran’s nuclear work in exchange for fewer lifts on sanctions. Neither story says the goal of those other arrangements were expressly to “reduce pressure on Iran,” but rather reports on ongoing diplomatic discussions and considerations between Tehran and Washington.

The senator also asked to see internal State Department documents instructing staff to refer to Israel’s deals with Arab nations as “normalization agreements” and not the “Abraham Accords” — though the Biden administration still uses the Trump-era term. Leaf said she was “not in a position” to share such documents as a nominee, but said she would “respond to your concerns” once confirmed by the full Senate.

The State Department’s long-standing view is that it's not within a nominee's authority to hand over documents to a Congressional committee. Only the agency can do so.

Cruz also asked three questions about Egypt, but his main one was about the 16 individuals detained by Egypt in what the U.S. has flagged as a gross human rights violation. He wanted to know if the $130 million the U.S. is withholding from security aid to Cairo is contingent on their release, as well as the names, affiliation and specific charges against those individuals. Furthermore, he’d like to know if any of the 16 people are members of Islamist groups and whether the administration intends to grant them U.S. visas if they were to be released.

Leaf’s long answer to those queries didn’t please Cruz’s team — and neither did any of her answers overall. “Leaf wrote back responses running to almost a thousand words. She answered 0 of the questions,” notes the two-page document.

“We asked the State Dept. to have her take another run at the questions — the point was to get answers, not do gotchas. They didn’t respond for a couple weeks, and then after Leaf was cleared they sent us an email saying that if we wanted rewrites my boss should lift his Nord Stream 2-related holds,” read the email from Cruz’s staff to Senate allies.