More than $1 million has been pledged in the last 24 hours to Rick Santorum, the fresh challenger to Mitt Romney's campaign to take on Barack Obama.
Mr Santorum's campaign appeared grounded until surprise victories in three selection contests catapulted him to the forefront.
Today the Santorum camp, energised by the financial boost, began sending teams of activists across the US to drum up support.
Mr Santorum's surge has been attributed to his anti-abortion, anti-gay rights stance, which has won favour with the powerful Right wing of the Republican party. But he remains a long shot, with Mr Romney still in the lead with the number of delegates he has secured.
There are fears in the Republican party that Mr Santorum's popularity could benefit Mr Obama, who faces a tough re-election campaign because of the weak US economy. Insiders believe a damaging nomination battle might weaken Mr Romney.
