U.S. Republican presidential candidate John McCain focused on the economy Monday, while Democratic rival Barack Obama canceled a campaign appearance because of mechanical problems with his plane.

McCain spoke at a town hall meeting in Denver, Colorado, where he reiterated his support for free trade and promised to see that U.S. citizens who lose jobs that go overseas are retrained through U.S. community colleges.

McCain also pledged to build 45 new nuclear plants, which he said will create 700,000 jobs while reducing U.S. dependence on foreign oil. Additionally, he criticized Obama's position on tax increases which McCain said will hurt the economy and destroy jobs across the country.

The plane carrying Obama and members of the press made an emergency landing in St. Louis, Missouri. Mechanics explained there was a problem with the plane's pitch - the ability to keep the plane level - but said passengers were never in danger.

Obama canceled his scheduled appearance in Charlotte, North Carolina, where he had been expected to call for a new stimulus package to boost the U.S. economy.

Obama's campaign also announced that he will accept the Democratic party presidential nomination at Mile High stadium in Denver on August 28, rather than at Denver's Pepsi Center where the Democratic convention will be held that week.

The Pepsi Center holds up to 21,000 people, while Mile High stadium accommodates around 75,000 spectators.

Some information for this report was provided by AFP, AP and Reuters.