Forty-four percent of registered voters held a favorable view of the Republican Party, compared to 43 percent for the Democratic Party. While the Republicans' favorable rating is similar to that before the party conventions started in 2008, the Democrats' is 11 percentage points lower than 2008, according to the USA Today/ Gallup poll conducted on Aug. 20-22, just ahead of the Republican National Convention in Tampa, Florida.

The favorability of the Democrats among the voters is at the lowest pre-convention level in Gallup records since 1992, the Gallup said in a report on the poll. The relatively low ratings for both parties likely reflect Americans' broader dissatisfaction with the country's direction and government leaders, including Congress, the Gallup said.

The independent voters are expected to be crucial to decide the result of this year's U.S. presidential election on Nov. 6. But the Republicans and Demorcrtats again have a virtual tie in terms of favorability among the independents, at 50 percent to 49 percent. The Republicans have a 38 percent unfavorability rate, in comparison with 37 percent for the Democrats.

More than 40,000 Republican delegates, activists and supporters are attending the three-day Republican National Convention in Tampa, which on Tuesday formally nominated former Massachusetts governor Mitt Romney as the Republican candidate to challenge President Barack Obama in the race for the White House.

Although the Republicans hope to raise Romney's ratings among U. S. voters through the carefully-staged convention, it remains to be seen if this year's convention will achieve the goal.

A recent Gallup analysis has found that the presidential candidate leading in Gallup polls prior to the first convention ultimately won the election in 12 of the last 15 presidential election contests, which suggests that the quadrennial conventions rarely change the overall trajectory of a race, the Gallup said.

The Democratic Party's national convention is expected to be held on Sept. 4-6 in Charlotte, North Carolina.