Biden prepares for campaign-defining NATO speech [Video]

WASHINGTON — President Joe Biden has a fresh opportunity Thursday to try to prove to the American public that he’s capable of serving another four years after his shocking debate flop threw the future of his presidency into doubt. But Biden is not known as a master of the big rhetorical moment and his recent cleanup efforts have proved inadequate.

Biden, 81, will close out the NATO summit in Washington — an event meant to showcase his leadership on the world stage — with a rare solo press conference. His stamina and effectiveness are under the microscope like never before and he’s struggling to quell the Democratic Party’s panic about his chances this November.

By many metrics, from job growth and major legislation to the expanded transatlantic alliance, Biden can point to successes during his …