The Senate voted 50-49 to repeal a rule that shields donors to many nonprofit groups from disclosure to IRS officials.

The dramatic vote was tied at 49-49 with 49 Democrats voting in favor and 49 Republicans against, when Sen. Susan Collins, R-Maine, cast the deciding vote to repeal the rule. Sen. Thom Tillis, R-N.C. was absent.

The resolution by Sens. Jon Tester, D-Mont., and Ron Wyden, D-Ore., would make use of the Congressional Review Act to repeal IRS guidance that would have allowed nonprofit organizations to omit names of major donors — those giving more than $5,000 — from disclosure statements, though they would still have to keep the information if the tax-collecting agency asked for it.

The guidance would have gone into effect next month.

Shortly before Collins broke the 49-49 tie and voted ‘yes,’ Sen. Rob Portman, R-Ohio, was speaking into her right ear, and Tester was speaking into her left.