(Reuters) - Republican Senator Jeff Flake’s surprise decision to drop out of next year’s U.S. Senate race in Arizona could be bad news both for the Republican who was challenging him and for the Democrat seeking to win the seat for her party. Republican Kelli Ward and Democratic U.S. Representative Kyrsten Sinema had, in their own ways, each been counting on Flake’s unpopularity in their quest to win the November 2018 election. “It was a bad day for Kelli Ward and a bad day for Kyrsten Sinema,” said Stan Barnes, a veteran Republican political consultant in Arizona. Flake’s departure has raised the stakes in the contest for one of only two Republican-held Senate seats that Democrats appear to have a good chance of flipping in 2018. Republicans hold a 52-48 edge in the Senate. Ward, an anti-establishment candidate backed by Steve Bannon, the former strategist for Republican President Donald Trump, had targeted Flake from the right. The former state senator was leading Flake in opinion polls for next year’s Republican nominating primary. Sinema, a moderate Democrat, had counted on facing either a wounded Flake, whose feud with Trump damaged his standing among Republican voters, or Ward, whom many political analysts doubt could prevail in a general election. Now Sinema faces the prospect of a more moderate Republican emerging to challenge Ward and, potentially, become the party’s nominee. Sinema’s campaign did not immediately respond to a request for comment. Ward “could win a primary, but she can’t win a general,”  Jennifer Duffy, who analyzes Senate races for the Cook Political Report in Washington said. “Please remember that Trump only carried the state by 4 points. You can’t have a nominee who’s out there.” The battle between Flake and Ward had been seen as the latest illustration of an ideological split between mainstream Republicans and the party’s anti-establishment wing. In Alabama last month, a far-right Bannon-backed candidate defeated an incumbent Republican in the party’s primary for a December U.S. Senate election. Flake announced his retirement on Tuesday in dramatic fashion, delivering a speech on the Senate floor that harshly criticized Trump’s behavior and his own party for failing to call it out. His decision not to seek re-election immediately prompted speculation that a number of Arizona Republicans would consider entering the race against Ward. In an emailed statement, Ward said her campaign was already surging even before Flake’s withdrawal. “Other Republicans may decide to jump into the race at this late point, but it’s not something we’re worried about,” she said. “Arizona is ready to have a true conservative represent them in the Senate.” Republican consultants in Arizona said it would take weeks for the new contours of the race to take shape, as potential candidates weigh their chances, conduct internal polling and, perhaps, quietly consult with one another. Constantin Querard, a Republican strategist, said he found it unlikely that many candidates would rush to enter the race after having declined the chance to go after the unpopular Flake months ago, when it seemed likely that Trump could throw his support behind a challenger. “There are no obvious names put forth today that are any different from all the names bandied about when they were looking for someone to take on Flake in the first place,” he said. “But there will still be some – and if any is a solid conservative, they will become the odds-on favorite.” Duffy said the strongest Republican recruit was likely Representative Martha McSally, a retired Air Force colonel and  strong fund-raiser who is seen as a rising star in the party. But Duffy declined to predict whether McSally could beat Ward among a very conservative Republican primary electorate. “I stopped betting, oh, about November 8 last year,” she said, referring to the presidential election that Trump won in an upset. 