With his unexpectedly strong third-place showing in the Iowa caucuses, Marco Rubio demonstrated that he's the Republican establishment's best shot to scuttle the Donald Trump and Ted Cruz insurgencies. And now, in the aftermath of Iowa, thoughtful critics of that establishment, from the liberal Jonathan Chait to my paleoconservative colleague at The Week Michael Brendan Dougherty, have begun to describe Rubio as the second coming of George W. Bush.

The comparison makes sense in a purely formal way. Like W in 2000, Rubio promises to unite the party's grumpy, warring factions (which have grown much grumpier and more belligerent over the past 16 years), making Rubio a strong consensus choice within the party. It's also true that this formal unity would be built out of the same old planks that have formed the party's platform since Reagan's first election: deficit-fueled tax cuts for upper-income earners, strident military interventionism abroad, and lots of speeches (but few policies) in support of traditional faith and families.

But this obscures the fact that substantively, Rubio is far, far more right-wing than George W. Bush ever was. That Rubio has a chance of serving as a consensus candidate positioned somewhere near the ideological center of his party is a tribute to just how far right the GOP has lurched since Bush left office seven years ago.

Here are five areas where Rubio clearly and sharply outflanks W on the right.

1. Bush signed Medicare, Part D into law, vastly expanding drug benefits for millions of Americans. Rubio, by contrast, has promised with great fanfare that he will eagerly work with Congress to repeal the Affordable Care Act, which would strip millions of Americans of health insurance. It's also true that, like all the Republican presidential candidates, Rubio talks vaguely about replacing the ACA with a wonderful, unspecified market-based alternative. But no informed commentator on either side of the issue expects any Republican proposal to strive for coverage of as many people as the ACA currently does — let alone as many people as it would have covered if a series of Republican governors hadn't refused to participate in the law's expansion of Medicaid.

2. Bush cut taxes drastically. Rubio, meanwhile, would cut them…even more drastically. How much more? His proposed tax cut amounts to more than three times the size of the Bush tax cuts, with nearly half of it going to the top 5 percent of income-earners. These cuts would produce a revenue shortfall of $6 trillion after 10 years. That's an amount that even staunch conservatives have described as "huge" and "irresponsible."

3. Pro-lifers loved Bush, and for good reason. He appointed a string of conservative judges to the bench, and he spoke frequently about how every child, born and unborn, should be "protected in law and welcomed in life." Yet on abortion, too, Rubio manages to place himself several steps to Bush's right, refusing to permit exceptions for terminating pregnancies in cases of rape or incest.

4. For all of Bush's manifest foreign policy failings, he consistently upheld the distinction between the religion of Islam and terrorists who murder in its name. Compare that to Rubio, who has picked up the bad habit common to post-Bush Republicans of speaking much less precisely and responsibly about the supposedly severe danger that Muslims pose to the United States. Rubio has even suggested that the federal government should shut down any place that Muslims gather to be "inspired," including mosques — a move that would place Rubio on a collision course with several clauses of the First Amendment.

5. Rubio resembled Bush most closely in the months following the 2012 presidential election, when the junior senator from Florida took on a leadership role in the Senate's efforts to revive a failed initiative of W's second term — a reform of the nation's immigration laws, including a push to devise a path to citizenship for undocumented immigrants. The reform effort failed, and his role in it is now widely presumed to be Rubio's greatest electoral liability. (Sort of like how the rightward listing GOP treated Mitt Romney’s signature achievement as governor of Massachusetts as a potentially fatal electoral defect during his 2012 presidential campaign.) The result? On immigration, too, Rubio now finds himself far to Bush's right, railing about the need to close and seal the nation's southern border before even beginning to talk about any other kind of reform.

The lesson? Don't oppose Rubio because his presidency would amount to a third term for George W. Bush. Do it because a Rubio presidency would be a whole lot worse.