For the second time in two days, Senate Republicans on Tuesday blocked legislation aimed at making campaign groups more transparent.

In a party-line 53-45 vote, the Senate killed the DISCLOSE Act. It needed at least 60 votes to move forward.

Republicans said the DISCLOSE Act would discourage free speech by intimidating donors. The bill would have prevented outside campaign groups from hiding their donors by requiring organizations that spend $10,000 or more during an election cycle to file a report with the Federal Election Commission within 24 hours and identify any donors who gave $10,000 or more.

“It is a predictable response,” Lisa Gilbert, Deputy Director at Public Citizen’s Congress Watch division, told Raw Story. “It’s a false claim. Only those who have something to hide think that disclosure harms free speech.”

“Disclosure is obvious, easy and Americans want it,” she added.

Sen. Lamar Alexander (R-TN) said the “real solution” was to eliminate the limits on contributions to individual candidates. The Supreme Court’s controversial Citizens United ruling struck down limits on independent political spending — giving rise to Super PACS — but the court left limits on direct campaign contributions intact.

Alexander said that if the limit on contributions to candidates was eliminated, then everyone would be “encouraged to give their money directly to the campaigns, which must disclose contributions in ways that don’t discourage free speech.” Currently, individuals can only contribute a maximum of $2,500 to a candidate per election.

But Gilbert said removing campaign limits would only make it easier for even more money to flood into the political system.

“There is no evidence to state that if we removed campaign limits suddenly people would choose to give to candidates and campaigns instead of other avenues like Super PACs and 501(c)4 [nonprofit social welfare organizations].”

The DISCLOSE Act would have prevent partisan “social welfare” organizations like Karl Rove’s Crossroads GPS from being able to hide wealthy donors.

The IRS requires that nonprofit “social welfare” organizations “operate primarily to further the common good” and the organizations are prohibited from running ads in support of or opposition to candidates for public office. But groups like Crossroads GPS have attempted to circumvent the ban on partisan activities by attacking Democratic candidates in ads without explicitly urging people to vote against them.