On Tuesday, the Senate's 2016 Republican presidential candidates had to choose between business interests and support of free trade, and their lack of faith in President Obama's ability to negotiate a deal.

The trade debate presents a delicate balance for Republican candidates who have built their campaigns on assailing the Obama administration on everything from health care to foreign policy. Suddenly, they have found themselves pressured to support Obama out of commitment to free trade and at the behest of businesses key to their early success in 2016.

The tightrope was perhaps most clearly exhibited Tuesday by Sen. Rand Paul. The Senate voted against moving forward with the trade deal Tuesday afternoon, with a 52-to-45 vote blocking the advance of Trade Promotion Authority, the so-called "fast track" legislation that gives the administration more authority on trade by restricting Congress's voice to a simple up-or-down vote on any deal that is struck.

Paul voted to advance the bill, even after he told his leadership that he was a "no" on TPA, emphasizing how wary he was about what would be included in the proposed 12-nation Trans-Pacific Partnership and other future deals. Paul told WMUR, a television station in Manchester, N.H., that TPA would give "blanket authority on stuff we haven't seen."

But according to The Wall Street Journal, the U.S. Chamber of Commerce had made courting Paul's support a key goal as it lobbied members to get behind the legislation. And Paul has teetered around on trade policy before. As National Review pointed out, Paul once voted against an amendment that limited Congress's role in trade deals, only to turn around less than a month later to cosponsor a bill that included the amendment.

Paul wasn't alone in choosing not to block the Obama-backed initiative. Sen. Ted Cruz also voted to move forward with the trade package. It was hardly a surprise, as both Cruz and fellow presidential candidate Marco Rubio had touted their support for TPA in op-eds, speeches, and in interviews. Rubio, who has a fundraiser in Florida Tuesday night, missed the vote, but he had prepared a letter for the White House last month showing his support.

Before the vote, Cruz said he was backing the package because it had economic repercussions back home.

"In my home state of Texas, there are over 2.2 million jobs that depend on exports," Cruz said. "Trade benefits farmers, it benefits ranchers, it benefits manufacturers. When we open up new markets across the globe, it creates jobs and economic growth and opportunity here at home."

But Cruz was also careful to thread the needle between being pro-business and still being a vocal critic of the Obama administration. When asked if he trusted Obama to negotiate a trade deal, Cruz said that he believed the administration could "do very little," yet he was comfortable enough that Congress would have a vote on any deal the president negotiated.

"The next 20 months are going to be very dangerous. The Obama administration has proven to be the most lawless and abusive in history, but one of the few areas where this administration has been willing to support positive economic policies is in the area of international trade," Cruz said, before going on to criticize his Democratic colleagues for standing in the way of TPA. Cruz jokingly classified President Obama's disagreement with those in his party like Sen. Elizabeth Warren as "Democrat-on-Democrat violence."

Getting the support of all the 2016 Republican presidential contenders present was a rare bright spot for a White House that failed to garner support from many members of its own party on Tuesday.

While presidential contender Hillary Clinton has not taken a definitive stand on TPP, progressive Sen. Bernie Sanders, who recently announced his own campaign, was siding with liberals in his party like Warren.

"This will be a disaster for the American worker," Sanders said Tuesday. "On this issue, I believe that Elizabeth Warren is right, I believe that I am right, I believe that [Sen.] Sherrod Brown is right. I believe that all of us who are voting against fast-track are right. I think the president—who I have a lot of respect for and have worked with on many occasions—is dead wrong."

Alex Rogers contributed to this article

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