As Rand Paul threatened to “force the expiration of the NSA illegal spy program”, Barack Obama on Saturday made a last-ditch plea to Congress to pass a bill that limits some surveillance powers, saying it would be “irresponsible” and “reckless” to allow such authorities to expire at midnight on Sunday.

“This is a matter of national security,” Obama said in his weekly address. “We shouldn’t surrender the tools that help keep us safe. It would be irresponsible. It would be reckless.”

Obama blamed “a small group of senators [who are] standing in the way”, understating the gridlock in Congress caused by several groups who support or oppose the reform-minded bill, the USA Freedom Act, over a status quo renewal of powers under the Patriot Act.

Republicans and Democrats are divided into three primary factions that do not necessarily fall in party lines. Surveillance hawks, including Senate majority leader Mitch McConnell, want a clean, temporary reauthorization of NSA and FBI powers. Another faction, backed by the White House, supports the USA Freedom Act as a “reasonable compromise” between privacy and security.

A third Senate faction, including the Republican Paul and Democrat Ron Wyden, believe the USA Freedom Act does not go far enough in limiting surveillance powers.

On Saturday, while insisting he would not “obstruct”, Paul promised to block any version of the renewal of the authorities, suggesting another after-midnight debate on Sunday.

“I acknowledge the need for a robust intelligence agency and for a vigilant national security,” Paul said in a statement. “But we do not need to give up who we are to defeat them … There has to be another way. We must find it together.”

The Republican-led House of Representatives passed the bill with bipartisan support earlier this month.

Feuding between these groups prevented either a renewal of the Patriot Act or passage of the USA Freedom Act before a legislative recess, obliging senators to reconvene over the weekend for a final attempt to vote. On Friday, Paul suggested he would filibuster the vote and force the expiration of Patriot Act provisions.

The president framed the USA Freedom Act as a set of positive reforms, including the end of the NSA’s bulk collection of American phone records – as revealed in the Guardian by the whistleblower Edward Snowden – the transition of those records to telecom companies, and greater transparency regarding the mostly secret Fisa court decisions that authorize surveillance warrants for intelligence agencies.

The bill also has the backing of current and past intelligence officials, who prefer its changes to the lapse of some authorities.

But despite Obama’s characterization that “these tools are not controversial”, civil liberties advocates remain divided over whether to support the USA Freedom Act. Many privacy groups argue that the limited reforms of the bill only change the means through which the NSA and FBI can surveil Americans, and do not actually restrict their reach.

Holmes Wilson, co-founder of activist group Fight for the Future, said surveillance hawks had “looted” the bill of reforms. Prominent rights organizations are split, with some supporting the Freedom Act while others, including the American Civil Liberties Union and the Electronic Frontier Foundation, have declined to back the bill.

NSA dissenters also support the expiration of powers over the USA Freedom Act, as well as a more muscular reform bill.

Some senators have pushed for stronger reforms: Wyden by fighting to amend the bill to end warrantless “backdoor searches”, Paul by stymying his rivals with procedural blocks.

The Obama administration did not formally back the USA Freedom Act until after 7 May, when a federal appeals court ruled the bulk collection of phone records illegal under Section 215 of the Patriot Act. Obama had previously renewed full Patriot Act powers in 2010, and did not call for a review of them until after Snowden revealed the scope of intelligence programs.

In his address, Obama also suggested that personal politics, if not party ones, threatened to derail the bill.

“Some folks are trying to use this debate to score political points,” he said, likely referring to Paul’s presidential ambitions and the theatrical 10-hour speech he gave earlier this month on the NSA.