The longest-serving member of President Donald Trump's national security cabinet, Mike Pompeo is also his fiercest defender -- a tactic that has helped keep him in power within the administration for nearly four years now, even as that loyalty sometimes leaves him alone on the battlefield.

Pompeo played that role again on Thursday as the Secretary of State danced around a defense of Trump's tweet about moving Election Day this November because "Universal Mail-In Voting" threatens to make it "the most INACCURATE & FRAUDULENT Election in history," the president claimed.

During Senate testimony, Pompeo warned a "full in-mail balloting program" presented a "level of risk."

"I saw this in my home state of Kansas," he continued. "When you change the voting rules getting close to an election, it's a difficult task."

Pressed later by Sen. Tim Kaine, D-Va., about Trump proposing changing the election from Nov. 3, Pompeo said he was "not going to enter a legal judgment on that on the fly this morning" -- instead deferring to the Department of Justice and others to "make that legal determination."

"It should happen lawfully," Pompeo added.

But Kaine shot back: There is no way for a president to lawfully change Election Day because it is set by Congress, with a statute from 1845 still in effect.

"I don't think it's that hard a question or one that should lead to equivocation by somebody who's fourth in line of succession to be president of the United States," the former Democratic vice presidential candidate added, pointing out Pompeo was a top graduate of Harvard Law School.

Pompeo tried to jump in, but Kaine moved on to another topic.

For the secretary and other GOP leaders, it was a common defense of the president, steering to avoid alienating or upsetting the boss while not necessarily endorsing his idea.

What's striking is that almost no other Republican did the same thing Thursday.

The top Republicans in the House and Senate both dismissed the idea. House Minority Leader Kevin McCarthy, R-Calif., said, "We should go forward," while Senate Majority Leader Mitch McConnell, R-Ky., said, "Never in the history of the country, through wars, depressions and the Civil War, have we ever not had a federally scheduled election on time, and we'll find a way to do that again this Nov. 3."

Pompeo has sewn himself so tightly to Trump, rarely if ever breaking with him even when he personally disagrees on an issue, such as Trump's decision to pull U.S. troops out of Syria or to not retaliate against Iran for downing a U.S. drone.

That strategy has kept him around far longer than former colleagues like Defense Secretaries James Mattis and Patrick Shanahan, National Security Advisers H.R. McMaster and John Bolton, and of course, his predecessor, Rex Tillerson.

But critics like Sen. Bob Menendez, the top Democrat on the Senate Foreign Relations Committee, have also cast that closeness as a political strategy for Pompeo's personal aspirations, accusing him of upending U.S. foreign policy for domestic political ends.

While Pompeo was rumored by some to be considering a run for Senate in Kansas, he declined to join the race, with the June 1 filing deadline now passed. But he's been more open about his presidential ambitions, telling business leaders from the Economic Club last year, "There's nothing I wouldn't consider doing for America."

But walking that tight rope has put Pompeo in a tight position several times, instead trying to bulldoze through charges of hypocrisy or questions about confusing changes in policy.

He spent weeks enshrining the administration's push for the "complete, verifiable, and irreversible denuclearization of North Korea," only to face questions about Trump and North Korean dictator Kim Jong Un's agreement that fell short of agreeing to that goal; he dismissed them as "insulting and ridiculous and frankly ludicrous."

A hardliner on Iran, Pompeo repeatedly listed several changes from the Iranian government before any meeting between Trump and Iranian leaders. But ahead of the U.N. General Assembly in New York last September, he said there were "no preconditions" on a possible meeting with President Hassan Rouhani -- only for Trump to tweet days later he would not meet "'No Conditions.'"

Amid the coronavirus pandemic, he touted American contributions to the World Health Organization on March 31 as key to "protect Americans and keep us safe," but just weeks later, he and Trump started blasting WHO as disastrous and eventually announced the U.S. would withdraw from the U.N. agency.

That maneuvering was again on display Thursday before the Senate Foreign Relations Committee. He said Trump leads "the toughest administration ever on Russia," pointing to several policies meant to pressure the Kremlin. But asked about Trump's comments Tuesday that he's never raised the issue of Russia offering bounties to the Taliban to kill U.S. troops, Pompeo danced again.

"I always leave to the president what he wants to say to other leaders," he said.

Pompeo cast Trump's troop withdrawal from Germany as "threatening" to Moscow. When pressed on the Kremlin's spokesperson welcoming it earlier that day, he didn't respond, and Sen. Jeanne Shaheen, D-N.H., moved on.

Kaine used the same tactic to stop Pompeo from responding on Election Day by turning to former U.S. ambassador to Ukraine Marie Yovanovitch, who was disparaged by Trump and his lawyer, Rudy Giuliani, before being ousted.

After declining to offer any praise for the veteran ambassador, Pompeo sparred with Kaine over Giuliani's campaign against her. As the secretary smiled and at times chuckled, Kaine accused him of treating the issue as "just a big joke. I mean, hey, look at you, smiling and laughing and calling it silly."

This time, Pompeo did get the last word: "I don't think it's silly to the United States Department of State to understand that every ambassador, every political appointee knows that if the president of the United States finds that they lack confidence in you, the president has the right to terminate them. It's that easy. It includes me."