Ted Cruz at the Capitol last week. (AP Photo/Susan Walsh)

Ted Cruz would spend his first day in office trying to undo some of Barack Obama’s biggest achievements via executive order.

In a wide-ranging interview about how he’d spend his first 100 days as president if he won, the Texas GOP senator pledged to roll back more than just the president’s controversial orders related to immigration.

“If you live by the pen, you die by the pen,” Cruz said by phone Tuesday, as he traveled from Dallas to an afternoon tour of the Southern border. “Everything put in place by executive order can be undone by executive order.”

Cruz said he would use the transition to bring a team together “to engage in a careful, systematic review of each executive action and to rescind every one of them that exceeds the Constitutional and legal authority of the president.”

Cruz’s comments underscored the tenuousness of some of Obama’s biggest second-term accomplishments, enacted by executive order because of a Republican-dominated Congress. He’s the first of several presidential candidates to outline his governing priorities in an interview with PowerPost, a new Washington Post site that will focus on the intersection of policy and politics.

Other highlights from the interview:

Cruz promised to do whatever it takes to stop Iran from getting a nuclear weapon, which he calls “the single greatest national security threat to the United States.”

“On day one, I would expect to convene the national security team for a serious, careful, sober assessment of where Iran stands – how close they are to acquiring nuclear weapons – and to review every tool at our disposable to assure that under no circumstances does Iran acquire nuclear weapons,” he said.

On Israel, he responded to this week’s Supreme Court decision by saying that he would allow Americans born in Jerusalem to list Israel as their birthplace on passports. Though Republicans and Democrats have promised in the past to move the U.S. embassy from Tel Avis to the contested city, Cruz pledges that he would actually follow through.

The senator, who was the first major party candidate to formally announce his candidacy back on March 23, said he’s running to try “to get a mandate from the electorate” to push far-reaching tax and regulatory reform. He really wants to eliminate the Internal Revenue Service, which he believes would be possible with a flat tax, but he recognizes how politically challenging such a proposition would be. So he would want to get the public behind it through the primary and general election.

I intend to do everything possible to make 2016 a referendum on repealing Obamacare and adopting a flat tax,” he said.

Asked about his legislative priorities, Cruz said he would focus on tax and regulatory reform first. He would also push for Congress to “repeal every word of Obamacare.”

He described himself as “cautiously optimistic” that the Supreme Court will side against the government in King vs. Burwell on the grounds that the federal government has “illegally collected billions of dollars in taxes from Americans who do not owe them.” If the court invalidates coverage for millions now receiving health subsidies, Cruz said he wants legislation that would let states “opt-out of Obamacare” altogether.

Cruz promises on the trail to repeal the Common Core state standards.

“This administration has used Race To The Top funds to pressure states to adopt Common Core standards,” he said. “At the very outset, if I’m elected, the administration would no longer use federal authority to coerce states into adopting Common Core.”

Asked who he might appoint to his Cabinet if he were elected, Cruz said that engaging with that question in a detailed way would be like telling a woman on a first date what he would like to name his children.

“One step at a time,” he said.

But Cruz said he could definitely see picking some of his GOP rivals in the 2016 race for prominent posts.

“Any Republican president would be a fool not to look very seriously at the men and women who will be on that debate stage as very serious and even likely members of a Republican cabinet and even a Republican dream team,” he said.