Arizona has traditionally leaned towards the Republicans, thanks in part to the state’s popularity with elderly retirees, who tend to be more conservative. In the past 17 presidential elections, the Democrats carried the state just once, when Bill Clinton was re-elected in 1996. But changing demographics mean that the gap between the two parties has narrowed, as shown by the fact that Donald Trump beat Hillary Clinton there by just over 3% in the presidential election two years ago.
Sinema has tried to appeal to the centre ground, while McSally has targeted the Republican base. Sinema’s tactics seem to be working better, with 11 of the 14 latest polls putting her ahead. McSally is now attacking Sinema for some comments about people joining the Taliban that she made in 2003 and this could shift some voters, but it probably won’t be enough to overcome Sinema’s lead. So I’d recommend betting on Sinema to win with Paddy Power.