U.S. President Barack Obama and Republican challenger Mitt Romney remain neck and neck in four swing states that are likely to determine the winner of the White House race next week, according to a Reuters/Ipsos poll released on Saturday.

The Democratic incumbent and former Massachusetts governor are both making final dashes through the handful of states they hope to win to secure victory on Tuesday.

In one of the biggest prizes of the election - Ohio - Obama has a very slight lead over Romney with 46 percent compared to 45 percent support among likely voters, the poll showed.

In Florida, another big prize, they are tied at 47 percent.

In Virginia, Obama leads Romney 48 percent to 45 percent among likely voters. In Colorado, Romney leads Obama 47 percent to 45 percent.

All of the results are within the surveys' credibility intervals, a tool used to account for statistical variation in Internet-based polls.