Four leading Republican presidential candidates have pulled even with President Barack Obama in a new poll, signaling a close race in 2012.

In a Gallup poll released Monday, Mitt Romney leads Obama by two percentage points, 48 percent to 46 percent, Rick Perry and Obama are tied at 47 percent, and Obama edges out Ron Paul by two percentage points, 47 percent to 45 percent. Michele Bachmann trails the president four points, 48 percent to 44 percent.

The survey, which was conducted on Aug. 17 and Aug. 18, indicates that the race for president is going to be highly competitive, according to Gallup.com.

Gallup's generic presidential ballot -- measured six times this year -- shows a close race between Obama and a generic Republican presidential candidate, although there have been survey-to-survey variations on this measure, with the Republican candidate leading in June and July, stated the Gallup report.

Democratic and Republican voters remained loyal to their party's candidates. Democrats were more consistent in their support for Obama, irrespective of the Republican he was pitted against.

Republicans, on the other hand, showed more variation. Texas Gov. Perry held the most Republicans in a race against Obama (92 percent). Romney, the former Massachusetts governor, held 91 percent, Minnesota Rep. Bachmann 86 percent and Texas Rep.  Paul 82 percent.

Among independents, Romney and Paul led Obama by three points and Perry by two, but the president led Bachmann by six points.

Concerns over a faltering economy, discontent over the acrimonious debt talks and high unemployment rates have shaken Obama's job approval rating, which is hovering around the 40 percent mark. This is below the rating that any of the six incumbent presidents re-elected since Eisenhower have had at the time of the presidential election, added the report. However, Ronald Reagan and Bill Clinton also had approval ratings below 50 percent in August of the year before they were re-elected.

The first real votes for the Republican nomination, in Iowa, are more than five months away. Candidates like Sarah Palin, Rudy Giuliani and George Pataki may yet join the race. While it is evident that Obama faces stiff competition, Election Day is more than 14 months off.

In 1999, George W. Bush beat Al Gore in a Gallup matchup by 14 points.  The race ended tied, with Gore ultimately winning more of the national popular vote. In August 1995, Kansas Sen. Bob Dole was slightly ahead of President Bill Clinton in a Gallup poll, 48 percent to 46. On Election Day 1996, Clinton beat Dole by eight points. In August 1983, President Ronald Reagan was ahead of Democrat Walter Mondale by only one point, 44 percent to 43. Reagan went on to beat Mondale in a 59-41 landslide in the November 1984 election. In August 1979, incumbent President Jimmy Carter was tied with former California Gov. Reagan -- each getting 45 percent. Reagan ultimately defeated Carter by 10 points.

The new poll results are based on interviews with 1,026 voters on Aug. 17-18, as part of a daily track survey and has a sampling error of plus or minus four percentage points.