Ted Cruz has outraged his critics—again. Working with his frequent allies in the Tea Party caucus of the House of Representatives, Cruz scuttled a compromise bill on immigration last week. The bill would have increased funding for efforts to stop and reverse the recent surge in illegal border crossings from Mexico, but it contained no new provision for deporting illegal immigrants already in the United States. So, in response to pressure from Cruz and his allies, the House passed a much tougher bill—one that would, if enacted, make it easier to deport the so-called DREAMers, people who were brought into this country illegally by their parents, through no choice of their own, and who have lived their entire lives as Americans.

The House bill has no chance of becoming law. The Democrat-controlled Senate would not approve it, and President Obama has vowed to veto it in any case. But Cruz has again succeeded in defining the position of the Republican Party on a major national issue. That he has done so in just his second year in the Senate—where he ranks ninety-first in seniority—is testimony to his extraordinary influence. (I Profiled Cruz in the magazine, in June.)

Once again, Cruz found himself at odds with the Republican establishment, personified by John McCain, the 2008 Republican nominee for President. McCain has often pressed for a middle position on immigration, and as a leader of the Gang of Eight, last year, he crafted a compromise bill that would create a path to citizenship for millions of people now illegally in the country. By offering such an opportunity, this law would have gone much farther than the bill that Cruz and his allies scuttled last week. McCain has taken this position, in part, because he believes that his party cannot recapture the White House until it reaches out to the large and growing population of Hispanic voters.

McCain’s position on immigration is a latter-day version of his fight with Cruz over Obamacare. Last fall, Cruz engineered a shutdown of the entire federal government over his implacable opposition to the Affordable Care Act. In the most celebrated part of this effort, Cruz staged a twenty-one-hour quasi-filibuster to call attention to his fight (and to himself). McCain and others regarded the shutdown as a political and substantive disaster that only hurt Republicans’ political fortunes, in 2014 and beyond.

Cruz views these conflicts as political gold. To him, the Republican quest for moderation is a longing for political disaster. “It is amazing that the wisdom of the chattering class to the Republicans is always, always, always ‘Surrender your principles and agree with the Democrats,’ ” he said when I spoke with him. “That’s been true for my entire lifetime. The chattering classes have consistently said, ‘You crazy Republicans have to give up on what you believe and become more like Democrats.’ And, I would note, every time Republicans do that we lose.” In Presidential politics, according to Cruz, conservatives (Reagan, G. H. W. Bush in 1988, G. W. Bush) win, and moderates (G. H. W. Bush in 1992, Dole, McCain, Romney) lose. This is a debatable version of history, but it’s not an irrational one—and Cruz believes it sincerely.

To all appearances, Cruz is riding his fight with the Republican establishment into the 2016 race for President. He has established himself as the hardest of the hard-liners on Obamacare and on immigration. His likely rivals Marco Rubio and Rand Paul agree with Cruz on the health-care law (though neither invested as much as Cruz in the fight); on immigration, Rubio joined with McCain in the Gang of Eight, and Rand Paul has at least hinted at a softer line on the issue.

Which candidate, then, has a better story to tell Republican caucus-goers in Iowa? One reason that senators have traditionally had a hard time running for President is that it’s difficult for them to distinguish themselves in the muddled process that produces legislation. Who has genuinely accomplished anything in the Senate? Who’s a leader? Ted Cruz has an answer.