President Barack Obama criticized Senate Republicans for leaving a “politically motivated, willfully negligent vacancy on the Supreme Court” in an editorial published Tuesday, just as the short-handed high court settled in to hear the first arguments of the new term.

“The last time a Supreme Court seat was kept vacant through Election Day was in 1864. At the height of the Civil War,” Obama wrote in an op-ed for the Huffington Post. “So, this isn’t about precedent. This is about the obstruction of a broken Republican-led Congress.”

Obama nominated Merrick Garland to the Supreme Court in March to succeed the late Justice Antonin Scalia. Republicans in the Senate have refused to confirm Garland to the court, arguing that the next president should be allowed to choose Scalia’s successor, although some have indicated that they may be open to moving Garland forward during a lame duck session after the election.

“By hobbling the Supreme Court for what could be a year or longer, Republicans are eroding one of the core institutions of American democracy,” Obama wrote. “This cannot be the new normal.”

Obama also noted in the piece other issues on which GOP lawmakers have opposed him, including equal pay, background checks for gun buyers, immigration reform, minimum wage increases and LGBT rights, saying that Republicans “have traded progress for partisanship” through their continued inaction.