Senator Robert Menendez of New Jersey announced on Thursday that he would not run for re-election as a Democrat this year, bowing to intense political pressure and federal charges that place him at the center of an international bribery scheme.

But in a nine-minute video posted on social media, Mr. Menendez, 70, insisted he would be exonerated at a trial scheduled to begin in May and he left the door open to running as a political independent if he is cleared.

“I am hopeful that my exoneration will take place this summer and allow me to pursue my candidacy as an independent Democrat in the general election,” he said.

Still, Mr. Menendez’s decision to forgo the competition for his party’s nomination amounted to a painful concession that his political career was teetering on the edge.

He was all but certain to lose the June primary for his own seat. Nearly every Democratic ally has abandoned him in recent months, and two prominent Democrats — Representative Andy Kim and Tammy Murphy, the wife of Governor Philip D. Murphy — are trouncing him in primary polls.

“Unfortunately, the present accusations I am facing — of which I am innocent and will prove so — will not allow me to have that kind of political dialogue and debate with political opponents who have already made it a cornerstone of their campaign,” he said in the video on Thursday.