When Congress returns from a two-week recess early next month, much of the debate is likely to focus on the issue of raising the country’s debt ceiling. But lawmakers will also revisit a somewhat more unpredictable battle that they postponed several months ago: the extension of three controversial provisions of the Patriot Act counterterrorism surveillance law.

Congress in February passed a 90-day extension of the three key provisions of the law that had been set to expire at the end of the month. That extension is set to expire May 27.

One of the provisions set to expire authorizes the FBI to continue using roving wiretaps on surveillance targets. The second provision gives the government the ability to seize “any tangible items,” such as library records, in the course of surveillance, and the third is a “lone wolf” provision that allows for the surveillance of targets who are not connected to an identified terrorist group.

The short-term extension of those three provisions, which passed both chambers in February with overwhelming bipartisan support, was the result of a compromise worked out by congressional leaders in order to give newer members, including the 87 new House Republican freshmen, a chance to get up to speed on the details of the legislation.

Since then, the House Judiciary Committee has held two hearings on the Patriot Act in the past month; the panel has also held several classified briefings for members over the past few weeks, according to committee spokeswoman Kim Smith. No legislation has been reported out of the committee yet.

On the Senate side, the Judiciary Committee last month reported to the full body Sen. Patrick Leahy’s (D-Vt.) Patriot Act bill, which would extend the three provisions until December 2013. The Leahy measure would also enact several other changes including a December 2013 sunset on the use of controversial national security letters, which give the FBI the authority to demand customer Internet records from communications providers.

The committee vote on the Leahy bill was 11-to-7: the panel’s 10 Democrats and freshman Sen. Mike Lee (R-Utah) voted in favor while the other seven Republicans on the committee voted “no.” In the committee’s report, the seven Republicans noted that they ‘‘vigorously oppose the changes’’ that the Leahy bill would enact and pledged to “offer a number of amendments to limit the damage” that they said the measure would cause.

Democrats noted in the committee report that two of the Republicans who voted against the Leahy bill, Sens. John Cornyn (Texas) and Jon Kyl (Ariz.), had previously supported a similar measure during the last Congress.

The Leahy bill has yet to be scheduled for floor time in the Senate, but when it does come up, it is likely to be actively debated: after the 90-day extension passed in March, Senate Majority Leader Harry Reid (D-Nev.) pledged to devote a week of Senate time to debating and amending the Patriot Act legislation.

Sen. Rand Paul (R-Ky.), a libertarian-leaning freshman who voted against the short-term extension, said in February that he planned to introduce several amendments to the measure. Further details from Paul’s office were not immediately available.

Timing will also be an issue in the upcoming debate. The Senate is in session for all of May, but the House will have a week-long recess in the middle of the month. The House is also not scheduled to hold votes on May 27, the date the current extension expires, meaning that any legislation would have to pass the lower chamber before then if the provisions are to be renewed.

Congress faced a similarly tricky situation in February, when both chambers were on recess for the week before the Patriot Act provisions were initially set to expire.

The politics of the Patriot Act have not been easy to gauge: as a civil liberties issue, it frequently unites lawmakers on either end of the political spectrum who view the law as an infringement on citizens’ basic rights. Former senator Russ Feingold (D-Wis.) was one of the law’s strongest critics, as is Rep. Ron Paul (R-Texas), Rand Paul’s father.

House Republicans in February initially attempted to fast-track a measure that would have extended the Patriot Act’s three provisions through December 2011, but they did not anticipate the bipartisan opposition to the bill. While the measure won the support of 277 members, it fell short of the two-thirds majority needed for passage under fast-track rules, with 122 Democrats and 26 Republicans casting ”no” votes.