WASHINGTON: A potential Republican presidential contender in 2016 vowed Thursday to continue blocking confirmation of a series of ambassadorial and other diplomatic nominees despite the Federal Aviation Administration lifting a ban on US airline flights to Israel.

The State Department criticised the lawmaker. Sen. Ted Cruz said he wouldn't release the holds until the Obama administration answers his questions about the FAA's prohibition, which went into effect Tuesday after a rocket landed about a mile (2 kms ) from the Tel Aviv airport. The FAA ended the ban late Wednesday, after Cruz accused Obama of imposing an economic boycott of Israel while it is fighting the militant group Hamas in Gaza.

“There are still serious questions as to the decision-making that went in to the ban on flights and whether it was driven by political consideration at the White House or by objective expert opinion at the agency,” the Texas senator said Thursday.

Cruz is demanding to know why Israel was singled out, while commercial flights can still pass over Afghanistan, Pakistan, Yemen and Ukraine, where a Malaysia Airlines jet was downed, killing all 298 people on board.

The FAA prohibited flights over Ukraine's Crimea in April and has ruled out overflights of the east of the country since last week's crash.

Cruz also wants to see any communication between the FAA, White House and State Department to see if the ban on landings in Tel Aviv was designed to punish Israel or advance cease-fire efforts. Almost 800 Palestinians have been killed in fighting over the last 16 days, mostly civilians, according to Gaza health officials. Israel has lost more than 30 soldiers and at least two civilians.

For the second straight day, the suggestion of political motivation behind the flight ban drew a sharp response from the State Department. “It's just perplexing,” spokeswoman Marie Harf said of Cruz's action.

“The notion that he would put a hold on State Department nominees when he really has questions for the FAA just doesn't really make sense.“

The objective of the flight ban “was purely security and safety of American citizens, pilots, people on these planes,” she said.

“The nominees we have up in the Senate are for some very critical positions. They need to move forward. If everybody's concerned about our foreign policy, we need people in those positions.“

A day earlier, Harf called Cruz's comments “ridiculous and offensive. “

Catherine Frazier, Cruz's spokeswoman, fired back that Obama's foreign policy was itself “ridiculous and offensive. “

The holds mean Senate Democrats would have to convince at least five Republicans to join them to approve a new ambassador to Russia as well as ambassadors to key US allies including France, Norway, South Korea and Turkey. Envoys involved in arms control and nuclear nonproliferation also are affected. The reality is none of the nominations are priorities given the Senate's other competing interests and many will likely have to wait longer anyhow.

A larger Senate logjam over issues unrelated to foreign policy has brought confirmations to a crawl, prompting complaints from Secretary of State John Kerry and White House spokesman Josh Earnest.