Mr Romney rallied in battleground Florida, the day after the Government reported an unemployment rate of 7.8% in September, breaking a 43-month streak of joblessness of 8% or higher.
The report risked breaking Mr Romney's stride, gained in a strong debate performance days earlier.
Because the American presidential race is decided in state-by-state votes rather than by popular vote, such battleground states that do not reliably vote either Republican or Democrat will likely decide the race.
The president launched a lucrative and celebrity- studded two-day fundraising swing to Los Angeles and San Francisco yesterday, which will be followed by a campaign rally in battleground Ohio.
"There is exactly one month left to go until Election Day," said Obama campaign manager Jim Messina. "The stakes are too high for us to take our foot off the gas now."
Persistently high unemployment, long after the recession's official end, has been a key threat to Mr Obama. The improvement came as a relief to his campaign – and a tricky development for his Republican rival.