How were the Republicans able to block the Disclose Act, if a majority of the senators supported it?

According to an email I got from the office of Senator Chuck Schumer:

“I want to thank you for standing with us to build support for the DISCLOSE Act.

Over 350,000 of your fellow Americans joined you in signing the petition. That’s an incredible amount of support that really says something about how important people think it is to get secret money out of our elections.

I’m proud to say that dozens of my Democratic colleagues and I went to the mat for this, too, pushing the vote and speaking on the Senate floor for hours, going well past midnight.

In the end, a majority of senators supported the bill, but Republicans still blocked it.”