On Nov. 23, when President Obama addressed the nation to tout the deal his administration struck with Iran over its nuclear program, he credited bipartisan sanctions passed by Congress for making such progress possible.

“However, now is not the time to move forward on new sanctions,” he cautioned members of Congress. “Doing so would derail this promising first step, alienate us from our allies, and risk unraveling the coalition that enabled our sanctions to be enforced in the first place.”

The statement was just the latest twist in Obama’s tortured relationship with imposing sanctions on Iran.

In December 2009, as Congress moved on Iran sanctions, Obama's State Department sent a letter to John Kerry (then chairman of the Senate Foreign Relations Committee) expressing concern that pending legislation “might weaken rather than strengthen international unity and support for our efforts” to pressure Iran.

As legislation developed, the administration tried to soften it by exempting some countries that were cooperating with the Obama administration's efforts.

In June 2010, sanctions against Iran's energy and banking industries passed 408 to 8 in the House of Representatives and 99 to 0 in the Senate, making Iran a rare issue of bipartisan agreement in a period marked by acrimony among Republicans and Democrats.

Obama, seeking to firm up support among the pro-Israel community, declared at a May 2011 speech to the American Israel Public Affairs Committee: “Here in the United States, we've imposed the toughest sanctions ever on the Iranian regime.”

Later that year, Sens. Robert Menendez, D-N.J, and Mark Kirk, R-Ill., crafted a bipartisan measure imposing sanctions against the Central Bank of Iran. But the Obama administration aggressively fought the effort.

On Dec. 1, 2011, then-Treasury Secretary Timothy Geithner wrote a letter to the Senate Armed Services Committee expressing “the administration's strong opposition to this amendment because, in its current form, it threatens to undermine the effective, carefully phased, and sustainable approach we have undertaken to build strong international pressure against Iran.”

At a time when Washington was polarized by budget battles, the Senate voted later that day 100 to 0 to approve the amendment, and a boxed-in Obama signed it into law.

Throughout the 2012 campaign, Obama bragged about the sanctions whenever he wanted to bolster his claims that he was committed to preventing Iran from obtaining nuclear weapons.

“We've put in the toughest, most crippling sanctions ever,” Obama said during his Oct. 22, 2012, foreign policy debate with challenger Mitt Romney.

Now, after signing on to a deal with Iran that provides the terrorist-financing Islamist regime with billions of dollars in sanctions relief while allowing the nation to continue enriching uranium despite six U.N. Security Council resolutions calling on Iran to suspend all activity in that area, Obama is telling Congress to hold off on additional sanctions.

But both Democratic and Republican members of Congress have blasted the Iran deal. One of the big fears is that beyond any immediate financial relief, it undermines the psychology of the sanctions.

The effort to isolate Iran is meant to dissuade would-be investors from doing any business with the nation. But any loosening up of pressure could be viewed as a green light to businesses.

That’s why lawmakers want to pass a new round of sanctions set to kick in after the six-month agreement is over — as well as at any sign Iran is violating the agreement.

This would, in the words of one GOP aide, signal to businesses that there will be a “guillotine” waiting if they choose to invest in Iran.

Whatever happens next, the fact that Obama has been praising the success of sanctions that were passed by Congress over his objections and warnings has left him with little credibility on the issue.