The 2012 Republican presidential race heated up as latecomer Texas Governor Rick Perry formally announced his candidacy and Iowans weighed in for the first time on their expanding field of presidential hopefuls, picking US Representative Michele Bachmann as their top choice for the party’s nomination.

Barack Obama has urged his supporters to work “like our future depends on it” as the race for the White House focused on a few crucial battleground states at the start of its final week today.