Washington - US President George W Bush has been a no-show on the campaign trail as the election season comes to a close, with Republicans worried that his unpopularity will hurt their chances with voters heading to the ballot box on Tuesday.

Bush has not made any public campaign appearances with Senator John McCain or any other Republican running for office in the past few months, limiting his role to a handful of fundraisers behind closed doors.

As the campaign wrapped up over the weekend and McCain was working fervently to close the gap with Democrat Barack Obama, Bush spent his time at the Camp David presidential retreat away from the spotlight. He has no public appearances scheduled for Monday or Tuesday.

"We're realistic about the political environment that we are in," White House spokeswoman Dana Perino told reporters Monday. "We're not immune to the questions that you ask almost daily about popularity approval ratings. We're aware of it."

Bush's job approval ratings have been stuck in the mid-20 per cent range during the last year, hampered by the war in Iraq despite strong signs of progress and by the economic crisis that led to national and worldwide turmoil ahead of the elections. His ratings are the lowest since Richard Nixon.

Bush has been the focus of Democratic attacks throughout the campaign season. Obama ties McCain's policies to the current president. Democrats challenging Republican seats in Congress exploit their opponents' legislative records of voting with the White House.

McCain has also been critical of the Bush administration as he seeks to distance himself from the White House, and rebuked Obama in a final October presidential debate for his continued efforts to portray Bush and himself as one and the same.

"Senator Obama, I'm not President Bush," McCain said. "If you wanted to run against President Bush, you should have run four years ago."

No sitting president who completed two terms has been so devoid of campaign appearances for his party. Ronald Reagan campaigned aggressively for George Bush's successful 1988 campaign and Bill Clinton hit the stump for Al Gore in 2000.

Bush even voted for McCain through an absentee ballot rather than show up at a polling booth in Texas. Perino said Bush has closely followed the presidential campaign as well as congressional races, but is comfortable with not playing a role after 14 years of campaigns dating back to his days as governor of his home state.

The president has been focused on his economic recovery plans to ensure he hands over the reigns of government with the country in the best situation possible, and is preparing for a summit this month with leaders of 20 countries to address the global financial crisis, Perino said.

Bush has reconciled his lagging numbers in the polls with his convictions that he always led true to his values to do what he believed was best for the United States and national security, even if the "tough decisions" he made no longer sit well with the public.

"Everybody would like to be popular," Perino said. "We can all remember that back in high school, everyone really wanted to be popular - and some of us just weren't." (dpa)