WASHINGTON — In a break with longstanding tradition, the Senate Judiciary Committee on Thursday advanced a Pennsylvania attorney nominated to become a judge on a powerful federal court despite objections from one of his home-state senators, Democrat Bob Casey.

The nominee, David Porter of Pittsburgh, cleared the committee by an 11-10 vote along party lines, and now awaits confirmation by the full Senate. President Trump nominated Porter to sit on the Court of Appeals for the Third Circuit, which often serves as the final word on major questions of federal law in Pennsylvania, New Jersey, Delaware, and the U.S. Virgin Islands.

Porter has long been opposed by liberal activists, and Casey refused to support him.

By Senate tradition, senators have a strong say over judicial nominees from their home states and can register their objections by withholding their signature on a piece of paper known as a "blue slip." For decades, nearly all nominees who lacked that signoff were blocked, and that custom was strictly enforced by both parties under all of President Barack Obama's tenure and most of George W. Bush's two terms.

While it's not a law or formal rule, and some chairmen of both parties have worked around the custom, exceptions over the last three decades have been rare, according to the nonpartisan Congressional Research Service.

Porter, however, is now the fourth Trump nominee to advance out of the judiciary committee despite lacking a blue slip from one or both home-state senators.

The shift is another blow in decades of tit-for-tat escalation over the judiciary, and the tension now fueling the fight over Trump Supreme Court nominee Brett Kavanaugh.

Democrats have accused Republicans of further eroding Senate traditions intended to foster cooperation now that they hold both the Senate and White House. Democrats, in a similar position during much of Obama's time in office, honored GOP blue slips that stifled some of the president's judicial nominees. Sen. Pat Toomey (R., Pa.) used the custom to oppose an Obama nominee to the same circuit court in 2016, when the GOP controlled the Senate, and the nomination was stopped.

Toomey's objection, in March of that year, came as Republicans were also blocking Obama Supreme Court nominee Merrick Garland, and arguing that it was too close to that November's presidential election to consider new court appointments.

Republicans leading the Senate Judiciary Committee now argue that one senator should not have the power to stop the entire Senate from considering a nominee who would oversee cases in multiple states. They add that Democrats, including Casey, weakened the minority party's power on circuit court picks by changing Senate rules on the filibuster in 2013, when they were in charge and wanted to override Republican objections to Obama nominees. If those rules were still in place, Democrats would have more power to stop Porter.

Democrats at the time argued that Republicans had thrown up unreasonable roadblocks against Obama cabinet nominees and judicial picks.

Republicans last year made the same rule change for Supreme Court nominees.