U.S. presidential candidates John McCain and Barack Obama are focusing on the struggling U.S. economy, before returning to Washington for a Senate vote on a bailout plan for the U.S. financial markets.

Senator McCain, an Arizona Republican, told supporters in Missouri that the current financial crisis will turn into a disaster if the bailout legislation fails again in Congress. The House of Representatives rejected legislation on the bailout Monday.

In Wisconsin, Senator Obama said Americans are waiting for leadership from the White House and Washington on the crisis. The Illinois Democrat noted the failure of the legislation Monday led to a plummet on Wall Street that affects a wide spectrum of Americans.

He said the crisis is the result of greed and irresponsibility that has dominated Wall Street and Washington for years.

In other news, a new poll shows Obama leading McCain in three states - Ohio, Florida and Pennsylvania - that are critical to winning the White House.

The Quinnipiac University survey shows support for Obama jumped to 50 percent or more in those three states. The states are critical because they are rich in electoral votes and have a history of shifting support between Republicans and Democrats.

That poll was taken after Friday's presidential debate and during Monday's spectacular drop in the U.S. stock market.

Separately, a new national poll by The Washington Post and ABC News indicates the economic crisis has buoyed support for Obama, but gives him a slimmer lead, 50 to 46 percent.

McCain's vice presidential pick, Alaska Governor Sarah Palin, and Obama's running mate, Senator Joe Biden of Delaware, debate Thursday for their first and only scheduled face-off of this election.