A modest bump in popularity for U.S. presidential hopeful Mitt Romney from this week's Republican Party convention looks to be short-lived, according to a Reuters/Ipsos poll.

Democratic President Barack Obama regained a narrow lead on Saturday by 44 percent to 43 percent over his Republican challenger, former Massachusetts Governor Romney, in the latest daily installment of the four-day rolling poll.

Romney was ahead by one point in Friday's online poll and two points in Thursday's survey as his campaign came under a blaze of media attention at the convention in Tampa, Florida.