Arizona ? Sarah Palin lent her star power among fellow conservatives to former running mate John McCain in his tough Senate re-election campaign, telling a rally Friday that McCain pegged President Barack Obama right when he said the Democrat would swell the size of government.

McCain is facing the hardest election fight of his Senate career as he fends off a Republican primary challenge from the right. J.D. Hayworth, former congressman and conservative talk radio host, says McCain is too moderate for Arizona Republicans. Hayworth has tried to build support among conservative activists who identify with the tea party movement.

Palin appeared with McCain for the first time since the pair lost the 2008 presidential election.