WASHINGTON — Russia warned the United States Senate on Monday not to rewrite the new arms control treaty being debated on Capitol Hill as American lawmakers clashed about the politics of ratification in the waning days of the Congressional session. Republican critics of the treaty, known as New Start, offered more amendments to the treaty’s language on verification and launcher limits. But any change to the treaty text would require both countries to return to the negotiating table, and Moscow made it clear that senators had to accept the treaty or reject it as it is, without amendments. “I can...