U.S. President Barack Obama and Republican challenger Mitt Romney’s race to the White House remained too close to call with less than a week to the election, according to opinion polls on Wednesday.

Obama leads the national vote 47 percent to 46 percent, but more significant are the numbers in the vital swing states that will decide the election. The most recent Real Clear Politics average of polls in the 11 swing states put Obama ahead of Romney by less than one percentage point with 48.5 percent to 47.2 percent, well within the margin of error. Obama led Romney 48.9 percent to 46.6 percent in Ohio, and 48.2 percent to 47.7 percent in Colorado, while Romney led 49.1 percent to 47.9 percent in Florida and 47.9 percent to 47.4 percent in Virginia.

A poll released by Reuters/Ipsos on Wednesday showed Obama ahead by three percentage points in Ohio and two in Virginia.

The same poll had the president and Romney in a dead heat in Florida, and Romney ahead by one in Colorado.

Ohio, with 18 electoral college votes, is considered crucial in deciding the outcome, as a loss there would make Romney’s path to the White House considerably more difficult.

By John Power  (john.power@heraldcorp.com)