CHICAGO — A confident Rand Paul claimed new momentum Friday in his fight against government surveillance programs, just days ahead of his second Capitol Hill showdown in as many weeks.
The Republican senator infuriated leaders in his party last week by almost single-handedly delaying the extension of the antiterror law, the Patriot Act. Parts of the law are set to expire Sunday night, including the power to collect phone records.
In a interview between campaign stops Friday in South Carolina, Paul said voters are encouraging him to continue fighting the National Security Agency’s bulk collection programs when the Senate convenes Sunday.
‘‘I find a great deal of interest among Republicans who tell me the NSA ought to stop collecting our phone records, that it’s wrong,’’ he said by phone.
President Obama said Friday that a ‘‘handful of senators’’ are the only thing standing in the way of an extension of the key Patriot Act provisions. He does not want to be in a situation in which the government is unable to prevent a terrorist attack or catch a suspect because of Senate inaction.
Paul, a 52-year-old libertarian leader, is working to transform his efforts on Capitol Hill into political capital as he builds up his nascent Republican presidential bid.
He lashed out at Republican leaders this week in campaign stops across Illinois, Iowa, and South Carolina while intensifying fund-raising outreach to help cash in on the attention. In the midst of last week’s Senate marathon session, Paul invited supporters to buy $30 ‘‘Filibuster Starter Packs’’ with a bumper sticker, T-shirt, and a ‘‘spy blocker’’ for Internet browsers.
He has also seized the opportunity to put distance between himself and his party’s other presidential hopefuls.
Voters are noticing. ‘‘I think some of his ideas are a breath of fresh air,’’ said Corey Brooks, an African-American pastor on the South Side of Chicago, where Paul campaigned earlier in the week. ‘‘His views are diametrically opposite of what Republicans tend to say and do, and I think it’s a good thing.’’
Yet it is unclear how far his civil liberties focus resonates beyond the libertarian-leaning voters who supported his father’s presidential ambitions.
He stood on the Senate floor for nearly 11 hours last week, bucking leaders in his own party, to protest the National Security Agency’s collection program that tracks phone records.
His delay tactic forced Senate leaders to adjourn with no resolution on the Patriot Act.
Majority leader Mitch McConnell has summoned the Senate for a rare Sunday session just hours before the midnight deadline. Expiration would mean suspension of a program that collects data on every American landline call, as well as of two FBI programs to track terrorist suspects.
Paul’s allies hyped the session in an ad that likens the debate to a wrestling match.
‘‘Watch them battle it out under the dome on the floor of the United States Senate in the brawl for liberty this Sunday,’’ the narrator says in a professional wrestling-style ad produced by a super PAC run by Paul’s former campaign manager.
The ad superimposes Paul’s head on the body of a wrestler, while describing one Republican presidential prospect, Senator Ted Cruz of Texas, as ‘‘the capitulating Canadian’’ and depicting another, Senator Lindsey Graham of South Carolina, in a purple convertible.
In his travels this week, Paul accused members of his party for abandoning their small-government credo in the national security debate. He has also blamed Republican national security hawks for the rise of the Islamic State group.
In a radio interview that aired Friday, Governor Chris Christie of New Jersey said that people like Paul who oppose the Patriot Act ‘‘have a severe case of amnesia’’ regarding the 9/11 terrorist attacks. Another potential rival for the GOP nomination, Governor Bobby Jindal of Louisiana, said Paul was ‘‘unsuited to be commander in chief.’’