the private equity giant leads funding round in biofuel startup Coskata.

Surrounded by excited staffers and supporters, candidate remains his characteristicly calm self.

Eli Saslow | 8:37 p.m. ET

Barack Obama widened his lead considerably over John McCain in four key battleground states during the past three weeks, providing further evidence that the economic crisis has greatly enhanced the Democrat's advantage with just 21 days left before Election Day.

Obama holds double-digit margins over McCain in Minnesota, Michigan and Wisconsin and carries a nine-point advantage over his Republican rival in Colorado, according to polling conducted by Quinnipiac University for washingtonpost.com and the Wall Street Journal.

Obama's ascendancy in these key states mirrors his growing lead in national polling. The latest Washington Post/ABC News survey put Obama at 53 percent to McCain's 43 percent, while the daily Gallup tracking poll showed Obama holding a similar lead of 51 percent to 41 percent on Monday.

The latest polling confirms that the financial crisis and stock market crash that has gripped Wall Street and Washington over the past month has increased the importance of economic matters to voters -- particularly in the industrial Midwest -- and accrued almost exclusively to Obama's benefit.

In Michigan, more than six in ten voters said the economy was the "single most important issue" in deciding their vote. Among likely voters, Obama increased his lead over McCain from a four-point edge in a late September Quinnipiac poll to a whopping 16-point lead in the most recent survey.

Obama's 54 percent to 38 percent lead in Michigan helps to explain why McCain decided to pull down his ads and pull out the majority of his campaign staff from the Wolverine State last week -- choosing to fight, instead, in Pennsylvania, New Hampshire and Maine.

The data was similar in Wisconsin and Minnesota where Obama gained 10 points and nine points, respectively, in his margin over McCain since the September Quinnipiac poll; the Illinois senator led McCain in Wisconsin 54 percent to 37 percent, and held a 51 percent to 40 percent edge in Minnesota.

In both states, 58 percent of the sample cited the economy as the leading issue affecting their vote -- nearly six times as many as named any other issue. The Wisconsin number represents a significant shift from the seven-point advantage the Quinnipiac poll showed for Obama in the Badger State in the third week of September. It also stands in contrast to other recent poll data, including a CNN/Time poll done earlier this month, that showed Obama leading 51 percent to 46 percent.

The surveys also indicate that Obama is significantly more trusted on economic issues than McCain. In Wisconsin, 53 percent said Obama "better understands the economy" while just 32 percent chose McCain. The numbers were not much better in Michigan (52 percent Obama/35 percent McCain), Minnesota (49/34) or Colorado (51/39).

A majority of voters in each state said McCain had not shown "effective leadership" in dealing with the financial meltdown. Throughout the past several weeks, McCain has condemned financial executives on Wall Street, offered a few proposed remedies for the crisis, and briefly suspended his campaign to return to Washington to take part in White House talks over a $700 billion rescue plan.

McCain also is being badly hamstrung by a national political environment tipped heavily against his party. Just one in four voters in Colorado, Michigan, Minnesota and Wisconsin approve of the job President Bush is doing -- a number reflected in the Post/ABC News national poll where just 23 percent of voters voiced approval for Bush's performance.

For all of the media focus on the presidential debates -- the third and last of which will be held tomorrow at Hofstra University in New York -- the encounters seem to have had little effect in persuading voters.

In each of the four states, between 71 percent and 75 percent of voters said they watched the second presidential debate in Nashville, Tenn., last Tuesday night. And yet, in each of the four states more than eight in ten voters said the debate did not change their vote.

Nearly half of the voters in each state thought Obama had done a better job in the Nashville debate while less than one in five voters said McCain had won the debate.

The Republican problems in these four battleground states weren't limited to the top of the ticket.

In Colorado's open seat Senate race, Democratic Rep. Mark Udall holds a commanding 54 percent to 40 percent lead over former Republican Rep. Bob Schaffer. In Minnesota, Sen. Norm Coleman (R) has slipped into a dead heat with his Democratic opponent Al Franken; Franken stands at 38 percent to 36 percent for Coleman and 18 percent for independent candidate Dean Barkley.

The polls were conducted from Oct. 8-12. The sample sizes were: 1,019 likely voters in Minnesota, 1,201 likely voters in Wisconsin, 1,088 likely voters in Colorado and 1,043 likely voters in Michigan. Each has a margin of sampling error of plus or minus three percentage points.