WASHINGTON — Starting the month with nearly $134 million in the bank, Democrat Barack Obama enters the final stretch of the presidential election with a robust ad presence in 18 states and the flexibility to expand if the politics move him.

Republican rival John McCain has no wiggle room. His budget a fraction of Obama's, McCain is looking to stretch his advertising dollar wherever he can.

While Obama buys ads in expensive media markets such as Chicago, Boston and Philadelphia, McCain is trying to extend nine-day advertising commitments to 14 days in places like Green Bay and Madison, in Wisconsin, reducing his spending and the number of spots he airs.

McCain, who began October with $47 million in hand, was taking similar cost-cutting steps in New Hampshire. Democrats said they detected similar moves in Maine, Minnesota and Colorado. Obama leads in polls in all five states.

The adjustments indicated McCain, aware of his financial disadvantage, was beginning to focus on more closely contested states.