Yesterday, legislation to grant President Obama the authority to negotiate fast-track trade deals like the Trans-Pacific Partnership (TPP) survived a Senate cloture vote, 62-38. This bill had the unenviable distinction of being the target of three distinct filibusters.The first one got the most attention. Two days ago, Senator Rand Paul (R-Ky.) went to the Senate floor and announced that he was filibustering against legislation to extend key provisions of the Patriot Act. With help from sympathetic Republicans and Democrats, Paul held the floor for 11 hours and sparked a mini-debate over whether he was filibustering or not.

In my research, I define “filibustering” as delaying action in a legislative chamber for strategic gain. The latter criterion is obviously satisfied: regardless of the effect of Paul’s speech on the legislative process, he used the speech to raise funds and draw attention to his opposition to the Patriot Act. But did Paul actually delay anything? The “no” argument is that the Patriot Act wasn’t on the Senate floor; Paul’s speech was actually interrupting debate on the trade bill. Today’s cloture vote on the trade bill was already set in motion by a cloture petition filed on Tuesday, and Paul’s speech could not affect the timing of this vote.

The “yes” evidence is that Paul’s speech may have kept Senate majority leader Mitch McConnell from filing for cloture on bills to extend the Patriot Act until today, so (barring a unanimous consent agreement) the Senate won’t vote to begin debate on these bills until Saturday.

A key point of my book on filibustering, however, is that modern-day obstruction is based on virtual filibustering: Senators threaten to filibuster and thereby force the majority to muster a supermajority (currently 60 votes) to limit discussion on an issue. By this standard, Paul wasn’t “really” filibustering unless he voted against cloture. In doing so, he would be trying to drag out debate on the trade bill so there is less time left to deal with Patriot Act reauthorization, making it easier for him to drag out debate and thereby kill the bill(s) or extract concessions. I call this tactic a “buffer” filibuster:  senators block bill A to keep bill B off the floor.

In fact, Paul DID vote against cloture on the trade bill, although he probably had multiple reasons for doing so (four other Republicans voted “nay”).

A second set of senators who filibustered the trade promotion authority bill were Democrats who simply did not like the bill in its current form. They are concerned that the TPP will harm American workers more than it helps, and that the agreement will be stacked in favor of business interests. This fits our standard conception of why legislators filibuster: Senators try to block bills they don’t like. The notable point is that this filibuster is barely newsworthy. Rand Paul gets attention for speaking on the floor, but Democrats provided the bulk of the votes against the trade bill today and last week, when a cloture attempt failed 52-45.

A third “filibuster” against the trade promotion bill was waged by a group of six senators who support the Export-Import Bank and wanted legislation to reauthorize the Ex-Im Bank added to the trade bill so the House Republicans are forced to consider the issue before the Bank’s authority expires on June 30. These senators supported the trade promotion authority bill on its own merits but were willing to vote against it unless they won a concession on a different issue — a filibustering tactic I call hostage-taking.

This faction apparently won a concession from McConnell. Yesterday’s cloture vote stalled at 54-38 for a couple minutes, followed by six votes for cloture from the Ex-Im faction: Cantwell (D-Wash.), McCaskill (D-Mo.), Graham (R-S.C.), Coons (D-Del.), Murray (D-Wash.), and Heitkamp (D-N.D.). The price of these votes was a promise to bring up an Ex-Im reauthorization bill in the next month.

The takeaway point is that this is what it means to legislate in the modern Senate. In the aftermath of the 2014 election, optimists pointed to trade promotion/TPP as a possible achievement for the 114th Congress because Republicans, President Obama, and some Congressional Democrats can all agree on trade expansion. But to get this bill through the Senate, its supporters have to survive opposition from the President’s party, grandstanding by Presidential candidates, and ransom demands from senators who want to get their priority issues onto the chamber’s agenda.