No buses, hotels or campaign manager. Can Santorum win?

His campaign is stretched so thin he sometimes sleeps in supporters' spare rooms and even taps them for a lift to his own rallies. But Rick Santorum, one of the remaining contenders for the Republican presidential nomination, has reason to believe votes in three states today will give him fresh hope to carry on.

"We are running this campaign on a shoestring," Mr Santorum said with a smile after coming last in Saturday's Nevada caucuses, which gave another big win to the front-runner Mitt Romney. "But that is an insult to shoestrings".

His comments are more or less accurate. Mr Santorum, who eked out a narrow win in Iowa at the start of this nominating process, sometimes travels accompanied only by a press aide. His campaign manager is based in New Hampshire, his senior political adviser lives and mostly stays in South Carolina and he long since gave up having a national campaign headquarters – what remains is a post office box in Pennsylvania.

Yet the sack-cloth and sandwich image is helpful also, endearing him to his supporters who come mostly from the religious conservative wing of the party. Unfailingly affable on the trail, he is the underdog to the rich-elite Romney. He doesn't hide in a bubble; after the debates, for instance, it is usually Mr Santorum himself who wanders into the spin room to talk to the press.

Of late, reporters have not been terribly interested to listen. But now that Newt Gingrich's hopes appear to be fading again, that may change. Three states vote today: Colorado, Missouri and Minnesota. Latest polls show Mr Santorum either winning or coming very close to it in the latter two states. Colorado is leaning to Mr Romney but evangelicals in the mountain state may deliver a strong second place to Mr Santorum, a former Pennsylvania senator.

"The conventional wisdom tells us Mitt and Newt are the only choices in this race," said Michelle Malkin, a prominent conservative commentator based in Colorado Springs, a place known as being the "Vatican" of US evangelical Christianity. "These most recent polls clearly suggest Santorum, not Newt, is the strongest conservative alternative. Is it a long shot? Yes. Is it doable? Yes."

The challenge for Mr Santorum, 53, is to convince voters that it is he, not Mr Gingrich, who is the conservative alternative to Mr Romney. Daniel Cole, a party activist and columnist for the Colorado Springs Gazette, thinks he can do it. "The notion that Gingrich is the conservative or Tea Party alternative to Mitt Romney has been greatly overblown," he said. He notes also that Mr Romney's Mormon faith is a factor that may count against him.

The Romney camp sees a new risk. After weeks of focusing on Mr Gingrich, yesterday it sent out emails attacking Mr Santorum and arranged a conference call for journalists to pick over his congressional voting record. The Santorum team duly sent out an email declaring: "Santorum Surge Prompts Romney to use Attack Machine".

His best result today may come in Minnesota. The state borders Iowa and the Republican Party has a strong streak of conservatism. Among those predicting a Santorum win there yesterday was Minnesota congresswoman Michele Bachmann. "It looks as though there's a closing in," said Ms Bachmann, who abandoned the race after Iowa. "Some of these states are opening up".