Sen. Ted Cruz, the Texas Republican who lost a hard-fought campaign for president last year, has one fundamental problem: His political ambition far outstrips his likability and political skill.

In the 2016 primary, his rudeness to Senate colleagues, glaring opportunism and awkward interpersonal skills — as much as then-candidate Donald Trump — prevented him from capturing the nomination. His off-again, on-again endorsement of Trump in the summer of 2016 merely confirmed that he lacked the skill to conceal his own hypocrisy.

Realizing he’d made no friends and claimed no legislative achievements in his first four years in the Senate, Cruz decided this year he’d shed his image as an obstructionist grandstander and adopt the pose of a diligent dealmaker on health care, the issue he used to stage a government shutdown in 2013.

However, Cruz — perpetually convinced he is the smartest man in any room — failed to master the fundamentals of health-care policy, or to anticipate that fellow conservatives might actually stand on principle. As a result, his half-baked plan to permit insurers to offer unregulated plans so long as they offered one that conformed to the Affordable Care Act requirements belly-flopped.

It did not take long before major insurers lowered the boom on Cruz, blasting his plan in an unusual, joint letter:

“It is simply unworkable in any form and would undermine protections for those with pre-existing medical conditions, increase premiums and lead to widespread terminations of coverage for people currently enrolled in the individual market. . . . This would allow the new plans to “cherry-pick” only healthy people from the existing market, making coverage unaffordable for the millions of people who need or want comprehensive coverage, including, for example, coverage for prescription drugs and mental health services.”

They explained: “As healthy people move to the less-regulated plans, those with significant medical needs will have no choice but to stay in the comprehensive plans, and premiums will skyrocket for people with preexisting conditions. This would especially impact middle-income families that are not eligible for a tax credit.”

Surely Cruz could have consulted with insurers and independent health-care experts to determine whether his plan was viable. Perhaps he wasn’t interested in finding out the answer, or perhaps he proceeded in the face of obvious flaws. In any event, he cemented his image as a man with a personal agenda but no real policy expertise.

Even more disastrously for Cruz, he found himself outflanked on the right when Sens. Mike Lee, R-Utah, and Rand Paul, R-Ky., balked at the plan. CNBC reported:

“Paul actually said Wednesday that the Cruz amendment could make his problems with the Senate bill worse. The policy could drive up costs for people in the Obamacare markets . . . which the federal government would then have to step in and subsidize to prevent a death spiral.

“‘The impressions and the rumors that we’re hearing is that’s gonna mean a lot more money in insurance bailout fund and ultimately also mean some sort of price controls,’ Paul said, adding that was ‘foreign to any notion of capitalism.’ ”

Lee was blindsided by Paul’s last-minute changes. (“Significant daylight has emerged between the Senate’s dynamic conservative duo. Once shoulder to shoulder on health-care reform with his longtime friend, Utah Sen. Mike Lee, Texas Sen. Ted Cruz has decided to go his own way.”) At the very least, he wants more time to consider the Cruz amendment.

In sum, Cruz is left championing a bill that is substantively unworkable and shunned by more principled right-wing Republicans. Cruz’s machinations leave him politically isolated once again.

At some point, one has to ask whether elected office is really Cruz’s forte. He seems to lack the interpersonal skills and legislative judgment necessary either to impress ideological purists or to forge the common ground required for legislative accomplishments. Perhaps rather than run for reelection in 2018, he might snag a federal court nomination. The prospect of bidding him farewell might induce a majority of senators to confirm him.

Jennifer Rubin writes the Right Turn blog for The Post, offering reported opinion from a conservative perspective.