In 2013, freshmen senators Ted Cruz (R-Tex.) and Rand Paul (R-Ky.) seemed like two peas in a pod. Both railed at the NSA, backed the government shutdown, opposed intervention in Syria and championed the tea party faithful. But 2014 has been a different story.

WASHINGTON, DC - SEPTEMBER 10: U.S. Sen. Ted Cruz (R-TX) (L) and Sen. Rand Paul (R-KY) wait to speak at the "Exempt America from Obamacare" rally, on Capitol Hill, September 10, 2013 in Washington, DC. Some conservative lawmakers are making a push to try to defund the health care law as part of the debates over the budget and funding the federal government. (Photo by Drew Angerer/Getty Images) Sen. Ted Cruz (R- Tex.), left, and Sen. Rand Paul (R-Ky.) wait to speak at the “Exempt America from Obamacare” rally on Capitol Hill in September. (Photo by Drew Angerer/Getty Images)

Cruz has become a serious, vocal proponent of a tough foreign policy and harsh critic of President Obama’s approach to Iran and Russia. He gave serious speeches on the importance of standing up to Vladimir Putin and on the folly of expecting Iran to give away its nuclear weapons program without stringent sanctions and/or the threat of force. He recently introduced and led unanimous passage of a bill, signed by the president, to ban issuance of visas for terrorists seeking to represent their countries as diplomats. He wrote for Politico:

Thanks to President Obama for joining a unanimous Congress and signing S 2195 into law. This bill gives the president the authority to deny visas to United Nations ambassadors who are known terrorists, such as Iran’s recent nominee Hamid Aboutalebi, who was a participant in the 1979 hostage crisis. The government of the United States has thereby sent an unequivocal, bipartisan message that we will not tolerate the ongoing campaign of insult and antagonism from the Islamic Republic of Iran.

Nominating Aboutalebi to be U.N. envoy is only the most recent in a long series of hostile actions proving that Supreme Leader Ayatollah Ali Khamenei’s regime remains America’s enemy. This pattern began with the holding of 52 Americans for 444 days from 1979 to 1981, but it did not end there. It extends to Iranian complicity in the terrorist attacks on our armed forces in Beirut in 1983 and Saudi Arabia in 1996, as well as in Iraq and Afghanistan over the last decade.

Iran’s state sponsorship of terrorism has been accompanied by a drumbeat of vicious rhetoric by Iranian leaders against the United States and our allies, in which America features as the Great Satan and Israel as the Little Satan — both of whom would, in Khamenei’s ideal world, cease to exist. And all the while, there have been additional provocations, including the ongoing detention of three American citizens, Pastor Saeed Abedini, Amir Hekmati and Robert Levinson. Aboutalebi’s nomination is just the latest outrage.

Regardless of their periodic promises of moderation, we must keep this pattern of hostility firmly in mind in any engagement with Iran’s leaders. They have been explicit in their goal: to persuade the world to relax its economic sanctions without interrupting their pursuit of a nuclear weapon. Just this week, Iran’s President Hassan Rouhani said, “We will witness the sanctions shattering in the coming months.

In words that would have left some dumbstruck just months ago, he allowed that “Washington has, with some justification, gained a reputation for being hopelessly mired in partisan gridlock. But it is nothing short of inspiring to find that when confronted with such blatant evidence of Iran’s virulent anti-Americanism, we can stand together as one in the defense of our national security.” He even credited the president for signing, and Sen. Chuck Schumer (D-N.Y.) for supporting, the legislation.

Cruz remains a man on the move, making now frequent stops to early primary states. He remains well back in the pack of 2016 contenders, and some doubt he’d want to roll the dice immediately on a presidential run. However, he’s shown in 2014 that he can exercise a positive influence on his party and make a difference in the Senate. At the risk of adopting a phrase used by Democrats to praise Republicans who have “moderated” (Cruz hasn’t), he has “grown” in the job. His staff is confident and accessible, willing to display their candidates’ prowess on national security.

Rand Paul is going in the opposite direction. The drip, drip, drip of video releases featuring his extreme remarks in recent years continues with no end in sight. This week the conservative Free Beacon reported comments Rand Paul made in 2007 denying Iran was a threat to the United States or Israel, as well as his comments on “‘One World Government’ conspiracy theories, including theories about the Bilderberg Group, a closed-door annual conference that brings together influential political and financial leaders from around the world.” (We and others have reported on video of Rand Paul from 2009 relating his views on WWII, which also are in sync with far right-wing radical thinkers.) The report details his staff’s response, alternately insulting and defiant.

Meanwhile, a diverse array of conservatives bitterly criticize his choice of hires, his criticism of civil rights legislation and his foreign policy views. As Rich Lowry puts it, he may have some redeeming features, but “the foreign policy is a problem, and he’s going to be pulled two ways on a numbers of these issues, between pure Paulism and the Republican mainstream.” He is undergoing this trial at the very moment when Vladimir Putin is reminding U.S. voters that the presidency of the United States is no place for amateurs or intellectual confusion, as one commentator observed:

In his self-appointed national address answering President Obama about Syria, Paul claimed that Obama would ally with al Qaeda, which was a lie. He then opposed any effective U.S. response to Assad’s mass murder in Syria, for which Assad would be grateful. Then Paul opposed American economic aid to Ukraine, claiming this aid would help Russia, when the aid was designed to help stabilize Ukraine against Russia. During the 2016 GOP primaries, one or more Republican primary opponents will almost certainly suggest that Rand Paul is Vladimir Putin’s poodle.

So far the big losers in the Putin aggressions include freedom in Russia, which Putin is destroying, the integrity of international agreements, which Putin is attacking, the sovereignty of Ukraine, which Putin is undermining, the stability of global security, which Putin is destabilizing, and the presidential candidacy of Paul, who meanders between isolationism, opportunism, appeasement and incoherence citing Ronald Reagan as his guide.

The trickiest issue, however, may be Kentucky state law, which while open to interpretations, seems to preclude Rand Paul from running simultaneously for re-election and for president. His allies’ efforts to change the law have now stalled, and with Sen. Marco Rubio (R-Fla.) suggesting it is unseemly to run for two offices at once, Rand Paul may have to choose which he pursues. If confronted with the choice, Rand Paul, many would guess, will go for the presidency. He’s never shown much affection for legislating, nor will more years of “no” votes, opposition to mainstream national security positions and dashed hopes that he will moderate (e.g., he talks a good game about immigration reform but votes no) make him more electable in in future presidential runs. In a real sense it is now or never for him, and a failed presidential run could well end his years in elected office.

We should be wary of making hard and fast predictions about these and other standard-bearers. If nothing else, they prove that six months or so in politics is a lifetime. To Cruz’s benefit and Paul’s detriment, the passage of time can radically change voters’ perceptions and pols’ career trajectories. And sometimes the most self-destructive course is to announce your intentions, draw fire and angrily protest that critics should challenge your views.