Sen. Rand Paul, R-Ky., announced Friday he is moving ahead with plans to file a class-action lawsuit against the National Security Agency.

If Paul files his constitutional challenge in Washington, D.C., it's possible the lawsuit will be considered "in tandem" with an existing lawsuit filed by Freedom Watch founder Larry Klayman.

Klayman filed the first class-action lawsuit against the NSA's bulk phone record collection after Edward Snowden's leaks in June. He also filed a class-action lawsuit challenging the NSA's PRISM Internet program.

U.S. District Court Judge Richard Leon awarded Klayman a preliminary injunction against the phone program Dec. 16, but stayed implementation pending appeal. The "almost Orwellian" program "almost certainly" violates Americans' Fourth Amendment rights, Leon ruled.

The ruling pushed Paul – who began soliciting volunteer plaintiffs in June – off the fence. For six months, the prospective 2016 presidential candidate weighed either forging ahead with a lawsuit or sitting back and assisting with three already-filed lawsuits brought by Klayman, the American Civil Liberties Union and the Electronic Frontier Foundation.

As late as December, Paul hadn't decided which route to take. A senior Paul staffer said Leon's decision – which also found the plaintiffs have standing to sue – nudged him toward filing suit with his "hundreds of thousands" of volunteer plaintiffs.

The senior staffer told U.S. News several details about the scope and nature of Paul's lawsuit remain unresolved and will be ironed out by an assembled legal team that includes outgoing Virginia Attorney General Ken Cuccinelli.

Among the details Paul's legal team will decide is whether the lawsuit will focus exclusively on the NSA's collection of phone metadata or also target the murkier NSA Internet programs.

If the lawsuit is filed in D.C. federal court – rather than in Kentucky – "it is possible that [it] could be considered in tandem" with the Klayman case(s), the senior staffer says.

Klayman says if Paul's suit is filed in D.C., "it will undoubtedly be assigned to Judge Leon as a related case, so the cases will probably go in parallel in some ways."

But "we were the first to file the class actions and ours will take precedence in terms of how it proceeds," he says.

The "in tandem" scenario might mean joint hearings and court rulings, but the cases wouldn't necessarily be combined.

The Klayman and Paul class-actions were approached with different footwork. Klayman filed his suits on behalf of a handful of plaintiffs with the intention of seeking a judge's ruling defining the class as all customers of certain companies. Paul first solicited volunteers – along with their email addresses and donations – on the website of RAND PAC, his political action committee.

If Paul does not move quickly enough, it's conceivable Klayman's phone case could reach the Supreme Court on its own.

The Department of Justice filed an appeal of Leon's injunction ruling and Klayman says "we will be filing a petition [this week] to have the D.C. Circuit refer the whole matter to the Supreme Court as a matter of public importance and speed," which would mean skipping over the U.S. Court of Appeals for the D.C. Circuit.

But Klayman says he's pleased Paul decided to sue.

"To have a U.S. senator involved shows the severity of this matter," he says. "We welcome Rand Paul into this fight, we welcome anyone who wants to join us, we want everyone together on our bandwagon."

The ACLU's lawsuit against the phone record collection, filed in New York, faced a setback last month. U.S. District Court Judge William Pauley dismissed the case Dec. 27 and ruled the program is "lawful." The ACLU is appealing that ruling.