What happened to turn this widespread skepticism into trust?

I think there are three explanations.

First was the judicious White House decision to support a modification of the draft bill to give the Congress a role in the implementation of the deal that was missing in its original version. Second, the supporters were quite effective in convincing members of Congress that the strategic gains outweighed the risks to nuclear nonproliferation. Third and perhaps most important, was vigorous lobbying, especially the efforts of the increasingly influential Indian-American community.

The Bush administration—for tactical reasons—had largely kept Congress uninformed about the initiative to make India an exception to US nonproliferation legislation, a decision that deeply antagonized both Republican and Democratic legislators. They were also angry that the administration’s draft bill lacked Congressional oversight over a proposal that is a dramatic departure from long-established nonproliferation policy.

Heeding the advice of senior representatives from both parties who support the nuclear deal, the administration agreed to revisions that would require a Congressional vote on the actual US nuclear deal (which is still under negotiation). This vote will take place after a mandated report to the Congress on the results of the US Indian negotiations, as well the results of India’s negotiations with the International Atomic Energy Agency and the reaction of the 45-country Nuclear Suppliers’ Group.

The legislative process will involve first an up/down vote—probably to take place within the next month or two—on the principle of making India an exception to US nonproliferation policy. This then will be followed by another Congressional vote, probably late this year, on the deal itself.

... contd.