The nomination of John Bolton as ambassador to the United Nations ran into unexpected trouble last week when Republican Sen. George Voinovich called for more time for consideration, postponing a vote in the Foreign Relations Committee until next month.

While Republicans sing in near-unison that the roadblocks to Bolton’s confirmation are the result of partisan attacks by Democrats, the truth is that wavering members of the GOP – legitimately concerned about the nominee’s past suppression of intelligence, exaggerations and undisciplined approach to diplomacy – have slowed the process.

Voinovich’s desire to take more time on Bolton could end the chances of confirmation. Now it has been revealed that former Secretary of State Colin Powell has advised lawmakers that Bolton is problematic.

The list of problems is significant: He may have lied under oath to the committee, witnesses testified he tried to bully intelligence analysts into backing up exaggerations about Cuba’s biological weapons program, kept information from his superiors and engaged in a sort of public diplomacy that undermined official U.S. positions. All very bad things for an ambassador to the United Nations.

President Bush maintains in public that he still supports Bolton. But the time has come for Bolton to either step aside or for the administration to withdraw the nomination. Otherwise a conscientious Senate will be forced to deny his confirmation.