With a mere 26 per cent approval rating, Mr Bush was expected to keep a low profile in Mr McCain's campaign.
But as it turns out, the President has been a virtual no-show - except in just about every Barack Obama stump speech as the bogeyman and in Democratic television ads that regularly tie him to Republican candidates.
According to a Reuters tally, Mr Bush and Mr McCain have only appeared together in public three times for a grand total of 12 minutes since the President endorsed the Arizona senator on March 5.
'You can be sure that if George W. Bush was more popular, he'd be out there,' Mr Stephen Hess, a veteran of the Eisenhower and Nixon administrations, told CNN.
Celebrated among Republicans in the past for his success in motivating donors, Mr Bush was once sought after to headline fund-raising events, but has cut back on such activities this year and has not participated in one in almost two weeks.
Even Vice-President Dick Cheney, perhaps the most polarising figure of the administration, had a fund-raiser on his schedule on Saturday.
As Mr McCain and Mr Obama made their final pitches to voters this week, Mr Bush was spending time at the Camp David presidential retreat. He had no public events yesterday, not even an Election Day photo op - he cast an absentee ballot for Mr McCain last week, which the White House sent down to Texas to be counted.
On election night, he was expected to watch the returns on television at the White House with friends and celebrate First Lady Laura Bush's 62nd birthday.
White House spokesman Dana Perino said on Monday that the incumbent's invisibility was by design because 'the Republican party wanted to make this election about John McCain', which worked out well for Mr McCain who has tried hard to distance himself from the President.
Asked on Friday if Mr Bush feels unloved by his party, White House deputy press secretary Tony Fratto said: 'I haven't had this kind of conversation with him, but I don't believe he takes it personally. He's been in politics his entire life - he's been around it his entire life - and he knows that it's a rough-and-tumble business.'
It is a stark contrast to the farewell campaign tour of the last two-term GOP president, Mr Ronald Reagan, who left office with one of the highest approval ratings ever at the end of a presidency - 64 per cent.
Mr Reagan embarked on a marathon coast-to-coast campaign swing for Mr George H. W. Bush during the final weekend of the 1988 campaign.
'It was a celebration,' recalls Mr Ken Duberstein, who was Mr Reagan's chief of staff. 'It was almost a thank-you tour.'
Mr Duberstein, who is planning to vote for Mr Obama, said it must be difficult for the current President Bush to have seen that and know he will never get one of his own.
ASSOCIATED PRESS