Senator Bernie Sanders lambasted Donald Trump for giving Carrier tax incentives to keep 1,000 jobs in America.

The deal has widely been seen as a victory for Trump -- he mostly delivered on a campaign promise. But Sanders argues that Carrier and its parent company, United Technologies (UTX), are having the last laugh.

"In essence, United Technologies (parent of Carrier) took Trump hostage and won. And that should send a shock wave of fear through all workers across the country," Sanders said in an Op-Ed in The Washington Post on Thursday.

Sanders key point: If corporations want cushy tax cuts, all you have to do is threaten Trump and say "we're moving to Mexico."

"He has signaled to every corporation in America that they can threaten to offshore jobs in exchange for business-friendly tax benefits and incentives," Sanders wrote.

On Tuesday, Trump and Carrier announced that they had reached an agreement to keep over 1,000 jobs in Indiana that had been slated to be moved to Mexico.

Related: Carrier: Trump gave us "incentives" to save jobs

Carrier said it received "incentives" from Indiana, where Vice President-elect Mike Pence is still governor, but declined to specify exactly what sweetened the deal.

Sanders, who campaigned to fight corporate greed, criticized Trump for putting on "kid gloves" with Carrier and offer it tax incentives to stay -- a tactic lots of states and cities do.

Sanders points out that wasn't what Trump told voters.

"After running a campaign pledging to be tough on corporate America, Trump has hypocritically decided to do the exact opposite," Sanders wrote.

On the campaign trail, Trump frequently threatened to slap Carrier with a stiff 35% tariff if it moved jobs to Mexico. But during negotiations, Carrier depicted a friendlier Trump.

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"The incoming Trump-Pence administration has emphasized to us its commitment to support the business community and create an improved, more competitive U.S. business climate," Carrier said.

In total, United Technologies had planned to ship roughly 2,100 jobs to Mexico. Another plant located close by and also owned by United Technologies employs 700 workers had announced plans to move to Mexico. That second plant wasn't part of the deal.

Sanders broke news too. He plans to soon introduce a bill to Congress to prevent jobs from being outsourced to other countries. Sanders hinted that under the bill, corporations wouldn't receive federal contracts or be allowed to offer beefy bonuses to corporate execs if they outsource jobs, among other penalties.

"If Donald Trump won't stand up for America's working class, we must," Sanders concluded.