Republican race: Five wins put clear water between Mitt Romney and his top rivals Published on Thursday 26 April 2012 00:43 A FIVE-STATE sweep for Mitt Romney finally killed off a fading challenge to his Republican crown, as the de facto presidential challenger turned his guns on president Barack Obama. The wins prodded conservative rival Newt Gingrich into preparing his exit from the primary race, with campaign aides saying the former House speaker would formally pull out next Tuesday. It leaves the way open for Mr Romney to focus his attack solely on Mr Obama, a man he accused yesterday of delivering "false promises and weak leadership" to the American public. The White House incumbent delivered a pre-emptive rebuttal in a Rolling Stone magazine interview, during which he indicated that Mr Romney would not be able to backtrack from conservative stances delivered in the primary campaign. In the interview - due outtomorrow - Mr Obama paints his rival for the White House as someone who has tied himself to the most conservative beliefs of the Republican right. He tells the magazine: "I don't think that their nominee is going to be able to suddenly say, "Everything I've said for the last six months, I didn't mean." In the course of the primary campaign, Mr Romney has positioned himself in line with the right in his party on issues such as abortion, gun controls and gay marriage - a move away from his earlier, more liberal stances. "I'm assuming that he meant it," Mr Obama told Rolling Stone, adding: "When you're running for president, people are paying attention to what you're saying." The comments suggest that the incumbent's re-election campaign will focus on drawing clear ideological lines between the two men and less on characterising Mr Romney as a flip-flopper on the issues. But it was another positive night for the Republican frontrunner. Wins in New York, Pennsylvania, Connecticut, Rhode Island and Delaware added to his delegate count and further cemented his position. The the latest victories look to have finally convinced Mr Gingrich to give up on any lingering hopes that he could wrestle the nomination from Mr Romney. Yesterday, aides told Fox News the former House speaker planned to drop out early next week. The source added that Mr Gingrich would "more than likely" endorse Mr Romney despite harsh words being exchanged between the two men during the primary campaign. Mr Gingrich follows former Pennsylvania senator Rick Santorum in suspending his campaign, leading the way open for conservatives to coalesce behind one mainstream party candidate. Ron Paul remains in the primary race, but has long since been confined to its margins. With his serious rivals dropping out, Mr Romney has increasingly turned his attention to the election in autumn. Last night he told his supporters: "Over the last three and a half years, we have seen hopes and dreams diminished by false promises and weak leadership. Everywhere I go Americans are tired of being tired. Mr Romney will also be focusing on fundraising. At the end of March, his warchest stood at $10 million (£6.2m), compared with $104m commanded by Mr Obama. However, conservative groups are expected to bring some parity to the money situation, with tens of millions of dollars to be spent on ads attacking Mr Obama.