At Kirsten Gillibran's exploratory committee facebook page, it looks like 9 out of 10 comments are

[Honeycombe8]

114. He had to leave when Schumer joined Gillibrand, and she got others to jump on bandwagon.

The Senators don't each act alone. They work in groups and on committees. They rely on the other Senators in their party. Without the support of most of the Senators, and particularly Schumer, Franken would not have been able to function properly in the job. So he did the only thing he could do, for Minnesota.

When Schumer joined the fray, that was the death knell.

They all fell for the Republican manipulation, IMO. What was disturbing was that altho Gillibrand said the accusations were credible, there was a difference of opinion on that, AND they did not even speak to one of the accusers. Not even one of them. They didn't ask questions. The accusers did not swear in affidavits or in person...so it wasn't testimony under oath (which is not evidence).

In other words, Gillibrand was all too eager to get rid of Franken, who had not long before started receiving calls from the public for HIM to run for President. Gillibrand, who was planning to run, ....well, I think she was all too eager to get rid of a potentially strong opponent in her bid for the nomination.

As a consequence, she made it all but certain that she will not be the nominee.