WASHINGTON — So ends the half-century career of a flawed but resilient politician who won the White House in a razor-thin election and lost it four years later in a debate: Joseph Robinette Biden Jr. Biden, 81, now eases into a lame-duck presidency for the next six months, as the party he once commanded abandoned him in the span of a few weeks for an as-yet-unnamed candidate to carry the fight against Donald Trump. Biden’s collapse began with a June 27 debate against Trump, when he turned in a disastrous performance from which he couldn’t recover.

An elderly president with his mouth agape, he struggled to complete a sentence or finish a thought. One by one, Democratic leaders who watched in alarm broke their polite silence and openly called on him to step aside. Stunning as his fall may be, Biden may be better prepared than most to deal with repudiation.

Few presidents in history have endured as much tragedy and disappointment as the 46th. Biden’s life has careened between unexpected triumph and unimaginable loss. He won elections and lost them.

He built a family, lost part of it, rebuilt it, and lost part of it once more. Hardened by experience, Biden seems to grasp that political partnerships are transactional: They come with an expiration date. If you want a friend in Washington, “get a dog,” Biden said at an NAACP convention on July 16, invoking former Democratic President Harry Truman’s famous dictum.

Delaware to Washington Long before he was considered too.