The Senate this week holds a hearing on whether to confirm Ambassador Bolton to his post as America’s permanent representative at the United Nations. Mr. Bolton has been at the post for nearly a year, and the man we have our eye on is Senator Schumer.This time around the senators have the advantage of seeing Mr. Bolton’s record. Those who oppose him now have the burden of explaining exactly what in that record they find so objectionable. Is it the Security Council resolution he engineered to impose targeted sanctions on North Korea? The resolution is widely viewed as a blueprint for upcoming action on Iran both in its substance and in the fact that Mr. Bolton was willing and able to compromise away some provisions to win Chinese and Russian support.

Is it his limited success in implementing management reforms such as a new whistleblower protection program? Is it his unwillingness to sign off on creation of a farcical Human Rights Council that at birth was already more discredited than its predecessor, the Commission on Human Rights? Or that during his month-long stint as president of the Security Council he enforced work ethics like making everyone show up on time for meetings? Or maybe it’s his unwavering support for Israel, especially during the current crisis?

Mr. Schumer’s opposition to Mr. Bolton the first time around puzzled us.Both are radically smart individuals who care about the U.N. and are committed to keeping it at Turtle Bay, and Mr. Bolton has presented the best opportunity yet to save the world body by making it effective abroad and less offensive to the Americans who pay so many of its bills. It’s hard to see what has happened in the past months to justify Mr. Schumer’s opposition to Mr. Bolton, and recent will only make New Yorkers wonder, if a fight erupts over Mr. Boston, why senators are quarreling over one of Israel’s staunchest supporters in the diplomatic corps.

Mr. Schumer can turn lemons into lemonade, however, by taking the lead in pressing the minority leader, Senator Reid, to drop organized opposition to the nomination. The result, from Senator Schumer’s perspective both individually and as the head of the Democratic Senatorial Campaign Committee, would be an ambassador who shares Mr. Schumer’s fundamental goals and a floor vote that would give Democrats an opportunity to start projecting a long-lost sense of seriousness about foreign policy.