By By The Associated Press–25 minutes ago

WASHINGTON (AP) — For the second straight day Republicans have stopped the Senate from taking up legislation that would require outside groups spending hundreds of millions on campaign ads to reveal how much they spend and who their big donors are.

With Republicans united in opposition, Democrats had no chance of getting the 60 votes needed to advance the bill. But it gave Democrats an opportunity to press their case against the flood of mostly negative political ads financed by independent groups backed by wealthy benefactors.

The bill would have required groups spending more than $10,000 during an election cycle to file a report within 24 hours and identify those donating more than $10,000.

Republicans said the bill would lead to intimidation of donors and was tilted to favor union political spending.