Sen. Bernie Sanders, D-Vt., said Friday that Senate Majority Leader Mitch McConnell, R-Ky., delivered a major win for trade critics by announcing that the proposed Trans-Pacific Partnership trade deal would not get a vote in the Senate this year.

McConnell had previously said that the controversial deal negotiated by the Obama administration to lower trade barriers among 12 Pacific Rim countries would be voted on after the fall election, but on Thursday he told an audience in Kentucky that the vote was not going to happen after all.

"I welcome Majority Leader McConnell's announcement that he will block a vote in the Senate this year on the disastrous, job-killing Trans-Pacific Partnership. This is good news for American workers, for the environment and for the ability to protect public health," Sanders said.

McConnell's announcement is a potentially fatal blow for TPP since it means the deal would have to be re-submitted to the Senate next year in order to get a vote. In addition, both major party presidential candidates, Democrat Hillary Clinton and Republican Donald Trump, oppose TPP. President Obama had been counting on a vote by a "lame duck" session of Congress to get it approved before he left office.

McConnell made the announcement during an appearance before the Kentucky Farm Bureau. After arguing that trade deals have been a boon for the state's farmers, the majority leader said that TPP had "serious flaws (and) will not be acted upon this year." McConnell expressed hope that it would come up next year but only after it is "massaged, changed, worked on."

TPP has drawn opposition from liberal groups, especially labor unions and environmentalists, who argue the deal will speed up job outsourcing and undermine environmental protection laws. Obama faced major defections from Democratic lawmakers on the issue and was counting on support from GOP leaders, traditionally strong trade proponents, to get TPP through.

However, the deal drew lukewarm support from Republican lawmakers, and McConnell said earlier this year that the matter was too hot to take up before the election. Support continued to ebb for the deal among Republicans over the last several months. Sen. Pat Toomey, R-Penn., who is locked into a tough fight to retain his Senate seat, came out against the deal earlier this month.

The best hope for the deal now is that Clinton, a recent convert to opposing TPP, reconsiders it if she becomes president. Clinton, who had helped to negotiate the deal as Obama's secretary of state, initially shied away from the issue on the campaign trail, but came out against it last year after an unexpectedly tough primary fight with Sanders.

During the Democratic National Convention, Virginia Gov. Terry McAuliffe, a long-time member of the Clinton family's inner circle, said he expected that she would reverse herself on TPP once in the White House.

"I worry that if we don't do TPP, at some point China's going to break the rules, but Hillary understands this," McAuliffe said. "Once the election's over, and we sit down on trade, people understand a couple things we want to fix on it but going forward we got to build a global economy." The Clinton campaign called the remarks "flat wrong."