Now that Sen. Marco Rubio, R‑Fla., has dropped out, the only real Obamacare opponent left in the Republican presidential race is his Senate colleague Ted Cruz, R‑Texas. Donald Trump and Ohio Gov. John Kasich have zero credibility on Obamacare.

Front-runner Donald Trump promises that he would repeal Obamacare. He has also said he digs the socialized “single-payer” systems they have in Canada and the United Kingdom. He has also said he likes and would preserve Obamacare’s unpopular “pre-existing conditions” provisions, which are the centerpiece of the law and which erode the quality of coverage for the sick. Trump has even said he likes Obamacare’s individual mandate. That’s the law’s least popular provision, which is forcing millions of uninsured Americans to pay penalties.

Would Trump actually try to repeal Obamacare as president? Or would he wake up one morning and decide to expand it? Or to endorse independent Vermont Sen. Bernie Sanders’ single-payer plan? Depends on when you catch him, I guess.

John Kasich actually supports Obamacare, or at least half of it.

After Trump aired an attack ad claiming, “Kasich gave Ohio Obamacare,” Kasich posted a response on his website. Literally every word of it is false.

  • “John Kasich opposes Obamacare.” False. He has implemented every part of the law he could. When Ohio’s Republican legislature passed a measure prohibiting him from implementing Obamacare’s Medicaid expansion — half of the entire law — he vetoed it. He then implemented the Medicaid expansion unilaterally.
  • He expanded Medicaid because he “wasn’t going to leave Ohioans’ tax money in Washington so Congress could spend it on another state”? Nonsense. That’s not how Medicaid works — and Kasich bloody well knows it.
  • He “rejected a federal takeover of Ohio’s insurance regulations and rejected a federal takeover of Ohio’s Medicaid eligibility process”? False. The federal takeover occurred when Obamacare became law. Kasich capitulated by implementing those parts himself, when he should have refused.
  • “He sued the federal government to block” Obamacare? False.Ohio’s attorney general Mike DeWine sued on behalf of Ohio. Kasich’s name is nowhere to be found on that lawsuit.
  • Kasich “rejected a state Exchange”? False. Kasich wanted to implement an Obamacare Exchange. Ohio Republicans blocked him.
  • “He wants to repeal Obamacare”? False. Kasich proposes only to repeal half of Obamacare. He wants the other half — his beloved, costly and ineffectual Medicaid expansion — to stay.

Rubio promised to repeal Obamacare only to replace it with Obamacare-lite. His “replace” plan mimics Obamacare’s health-insurance tax credits and individual mandate, and would have preserved much of the law’s new government spending.

Still, Rubio at least has a record of actually fighting Obamacare. Trump has no such record, while Kasich has actively done everything he can to implement and protect it. When Rubio dropped out, that left only one Obamacare opponent in the race.

Cruz also fought to stop Obamacare in Congress. Most (in)famously, his push to defund Obamacare in late 2013 led to one of those periodic and fake government shutdowns. The move coincided with the spectacular debacle of the rollout of Obamacare’s health​care​.gov web site.

Cruz hasn’t done as much to fight Congress’ special Obamacare exemption as I would like. Nor has he introduced a “replace” plan — though he has made noises about expanding health savings accounts (HSAs) to improve healthcare and deliver a $9 trillion tax cut.

Yet few doubt his dedication to repeal. He makes it a prominent issue in his campaign. If you told Cruz that there is a secret “Obamacare repeal” button hidden in the Oval Office, he’d probably be pole-vaulting over the White House fence before you could finish the sentence.

I disagree with Cruz on many issues, often strongly. And other GOP candidates might have been better on Obamacare. Bobby Jindal, a health-policy wonk who became governor of Louisiana, was more knowledgeable and creative. As early as 2012, he proposed making birth-control pills available without a prescription. His “replace” plan remains the best I’ve seen from any candidate so far (ahem, Ted). But he dropped out early in the race.

On repealing Obamacare and replacing it with better healthcare, Cruz is the only credible candidate still standing.