The big news of the day is that Senator Ted Cruz is officially running for president. Not setting up an exploratory committee or any of that perfunctory foreplay, but actually running. “It is a time for truth. It is a time for liberty,” he said in a 30-minute speech at, yeah, Liberty University. “It is a time to reclaim the Constitution of the United States.” Cruz’s address was full of red meat for the conservative crowd. But other than his oratorical skills, Cruz is entirely unsuited to be president. Luckily for America, his candidacy is likely doomed to fizzle.

Cruz recapped his life story, focusing on the role faith plays in his life, before diving into his traditional conservative talking points. He asked the crowd to imagine "millions of young people coming together and standing together, saying, ‘We will stand for liberty'" and “instead of economic stagnation, booming economic growth.” He asked people to imagine the next president repealing Obamacare, abolishing the Internal Revenue Service, implementing a flat tax and “finally, finally, finally secur[ing] the borders.” The crowd cheered each time.

The rest of the Republican field, whenever they officially announce their candidacies, will probably make similar promises; it’s hard to picture a candidate winning the Republican nomination without vowing to repeal Obamacare. As the Washington Post’s Greg Sargent writes, the Republican primary will reveal whether Cruz’s policy positions are extreme within the GOP or whether he differs mainly in his tactics.

His positions, regardless of where they fall within the Republican Party, are ill-conceived fantasies. Take taxes. A flat tax may appeal to the conservative base but it entirely misrepresents the actual problems with the U.S. tax code. The tax code is complicated not because of its progressive structure but because it is full of deductions, exemptions and credits that make it hard to calculate your taxable income. Cruz promotes the flat tax by saying it “lets every American fill out his or her taxes on a postcard.” But the exact same could be said about a progressive tax system. Senator Marco Rubio, another presumptive presidential candidate, didn’t propose a flat tax in his recently released tax plan (although he did say he wants to get there someday) because doing so is just not feasible. A flat tax would need to be set at a high enough level to fund critical government programs, requiring a massive tax increase on the middle class and poor. That'd be a political nightmare.

On Obamacare, Cruz wants to repeal the law … and then basically see what happens. This is, of course, the Republican Party’s position as well. But it’s unacceptable as a presidential candidate’s health care agenda. If you want to repeal the health care law, you better have a replacement plan. The same goes with abolishing the IRS. A Cruz government would eliminate the agency but it would still collect taxes—somehow. Cruz has never said how that would work. Would there be a new agency to replace the IRS? Would it have employees? Who, after all, would collect all those postcards? All unanswered questions.

Yet above all, one particular position should disqualify Cruz—or anyone else who holds it—from the presidency: using the debt ceiling as a hostage device. Breaching the debt ceiling would be disastrous. It’s hard to forecast exactly what would happen, but we can somewhat forecast day one after default. The government would have to prioritize its payments. Do you withhold food stamps from low-income Americans? Delay Social Security checks? Maybe we should stop payments on infrastructure projects. Those missed payments would harm millions of Americans and cause mass disruptions around the country as cash flow problems cause companies to become insolvent. Over the long term, it would permanently raise our borrowing costs, making our interest payments more expensive. In short, it would be self-inflicted economic Armageddon. Cruz considers his willingness to risk that catastrophe a selling point, touting his role in opposing the debt ceiling hikes on his website.

Beyond his policy positions, Cruz has demonstrated himself to be particularly un-presidential. During the 2013 government shutdown, for one, he demanded that President Barack Obama defund Obamacare in return for keeping the government open and avoiding a default on the national debt. It was a ridiculous demand that elevated Cruz’s national profile and ended with Republican approval ratings cratering. In the process, he infuriated much of the Republican establishment—not the only time he has done that.

That episode wasn’t an outlier. Throughout his time in the Senate, Cruz has shown a distinct lack of interest in policymaking or governing. Instead, he has calculated every move to prepare for a 2016 run. Every politician considers the optics of their positions, of course, but Cruz has taken it to the next level, with little care for how his actions affected the Republican Party or his colleagues. In doing so, he probably doomed his candidacy. On Monday, Five Thirty Eight’s Harry Enten convincingly argued that Cruz’s extreme views and his few friends within the Republican Party make it highly unlikely that he will win the nomination.

And that means Cruz’s role in the Republican primary will likely benefit Democrats. He’ll pull the rest of the party to the right on immigration, taxes and health care. Moderates such as former Florida governor Jeb Bush may to resist the urge to adopt more conservative positions. In December, for instance, Bush said that the GOP candidates had to be willing to “lose the primary to win the general without violating your principles." But that position is easy to hold 23 months before the general election and more than a year before the first primary. It will become harder to sustain as Cruz and others repeatedly hammer the moderates.

In Cruz’s speech Monday, he never mentioned Hillary Clinton. Instead, he painted a bleak picture of America and its role in the world, saying that the American dream “is slipping away from our hands.” He sees a desperate need for a conservative president to “restore that shining city on a hill that is the United States of America.” Implied throughout: Democrats are ruining America. Yet his actions are only making a Hillary Clinton presidency more likely. The Senator who would hold the government hostage has become the candidate doing the same to his party.