AP/Cliff Owen
Paul used Senate procedure to successfully - and temporarily - block the chamber's push to renew parts of the Patriot Act on Sunday.
This caused three sections of the controversial surveillance bill, including the National Security Agency's bulk records collection program, to expire early Monday morning.
Needless to say, GOP senators who believe the NSA needs robust powers are not pleased. Politico documented many of their gripes.
"I know what this is about - I think it's very clear - this is, to some degree, a fundraising exercise," said Sen. John McCain (R-Arizona). "He obviously has a higher priority for his fundraising and political ambitions than for the security of the nation."
Sen. Dean Heller (R-Nevada) further accused Paul of theatrics last month, when the Kentucky senator launched a 10.5-hour filibuster that stalled the NSA bill.
"He could only raise money filibustering," Heller was quoted saying.
Even Majority Leader Mitch McConnell (R-Kentucky), who has endorsed Paul's presidential campaign, slammed the bill's critics for waging a "campaign of demagoguery and disinformation," according to The New York Times.
Darren McCollester/Getty Images
Though being so heavily criticized by his fellow Republicans would normally be a blow to a GOP presidential candidate, Paul is waging an unconventional path to the nomination. The libertarian-oriented senator has repeatedly blasted the Patriot Act for its "illegal" spying operations and was unapologetic in the face of Sunday's attacks against him.
"Tonight we stopped the illegal NSA Bulk data collection. This is a victory no matter how you look at it," Paul said in a statement. "While some will use fear and intimidation tactics, I believe there is nothing that prevents our intelligence community from continuing to safely guard our nation, while also respecting our Constitution."
And, as his critics charged, Paul used his campaign against the bill as a fundraising tool:
#StandWithRand Donate here >>> https://t.co/6oqxjFguew pic.twitter.com/PgKMZJ3vaO
- Dr. Rand Paul (@RandPaul) June 1, 2015