Ahead of "Super Tuesday" on March 6, Republican presidential candidate Rick Santorum appears to have caught up with the one-time frontrunner, former Massachusetts governor Mitt Romney, in the Republican primary races.

Santorum's recent gains, including a 10 per cent lead over Romney in national polls, could herald a huge upset in the Republican race.

A devout Catholic, Santorum has used his socially conservative views to win the support of Republican voters.

Using his religious views on abortion as a basis, Santorum has said pre-natal tests should not be paid for by insurance companies and has called climate change "political science" based on "phony studies".

Al Jazeera's Patty Culhane reports from Washington.