The Republican senator who suddenly sits at the center of the explosive Supreme Court debate promised Monday to oppose President Donald Trump's nominee should an ongoing federal investigation determine he lied under oath. Arizona Sen. Jeff Flake, who holds extraordinary leverage in the confirmation process, addressed Judge Brett Kavanaugh's future directly as he trekked across New England while exploring a possible run for president. Asked what would cause him to vote "no" on Kavanaugh, Flake pointed to "any evidence that corroborates" his accuser's story.