The September 1-4 US Republican National Convention has given Republican presidential hopeful John McCain a significant lift in polls, surveys released on Sunday showed.

A USA TODAY/Gallup Poll, which was taken over last weekend, showed that McCain was now leading Democratic opponent Barack Obama by 50 to 46 percent among registered voters, the Republican's biggest advantage since January.

It was a turnaround from the same poll taken just before the convention when McCain lagged behind Obama by seven percentage points.

But McCain's ties to President George W. Bush, also a Republican, remained a vulnerability.

In the poll, 63 percent of those surveyed said they were concerned that McCain would pursue policies too similar to those of the current president. Bush's approval rating was 33 percent.

The Rasmussen poll put McCain and Obama at a tie of 48 percent each, while a CBS survey showed the two were tied at 42 percent each.

Previously, McCain lagged behind in both polls.

(Xinhua News Agency September 8, 2008)