Opposition from Sen. George Voinovich, R-Ohio, to John Bolton nearly stopped his nomination in committee. But Voinovich eventually voted to advance the nomination to the Senate floor -- but without an endorsement from the committee.
The senator's letter Tuesday urged fellow Republicans, who hold a 55 to 44 majority in the senate, to vote against Bolton, the New York Times reported Tuesday.
"In these dangerous times, we cannot afford to put at risk our nation's ability to successfully wage and win the war on terror with a controversial and ineffective ambassador to the United Nations," Voinovich wrote.
He urged colleagues to "put aside our partisan agenda and let our consciences and our shared commitment to our nation's best interests guide us."
At least five Republicans would have to join Voinovich in opposing Bolton for the nomination to be defeated.