As the Senate prepares to consider anew the nomination of John Bolton as United Nations ambassador, Senators Schumer and Clinton are facing increasing pressure from pro-Israel groups to renounce another Democratic filibuster in light of the escalating war in the Middle East. The Foreign Relations Committee is set to hold a hearing on the nomination tomorrow, and several Democrats on the panel have voiced their unswerving opposition to Mr. Bolton's nomination. From New York's senators, however, there has been nothing but silence. Mr. Schumer and Mrs. Clinton voted to block Mr. Bolton's confirmation a year ago, but they have not...