Suddenly, Republican Mitt Romney has a viable path to victory in the tight battle for the White House.
Democratic President Barack Obama still appears to have the upper hand in the state-by-state fight to cobble together the 270 electoral votes needed to win the presidency in the November 6 election.
But Romney's recent surge in the polls after his strong performance in his first debate with Obama on October 3 has propelled the Republican into the lead or within striking distance in enough states to give him a reasonable chance of beating Obama to the finish line.
Ohio, long seen as the key to unlocking the White House, looms large in every victory scenario for either candidate - particularly Romney. Until the last two weeks, polls did not show Romney with enough support in other crucial states to give him a clear path even if he won Ohio.
But he has that now, as the campaign enters its final two weeks with eight states in play as toss-ups.
"Before the first debate the electoral math looked like a real reach for Romney. Today, it looks quite possible," said Peter Brown, a pollster at Quinnipiac University.
"Ohio is the big unknown, and it's Romney's biggest obstacle," Brown said. "If Romney can win Ohio, he's likely to win the election."
The changing map has led Romney to make some shifts in strategy.
He began moving some staff from North Carolina, a one-time battleground where he now has a solid lead, to other swing states this week. The former Massachusetts governor's campaign also bolstered its television advertising in Iowa and Wisconsin, where polls indicate Obama has slim leads.
The RealClearPolitics average of polls gives Obama a lead of at least four percentage points in states that account for 237 electoral votes, while Romney enters the final stretch with an edge of that size in states that represent 206 electoral votes.
That leaves a reduced battlefield of eight toss-up states and 95 electoral votes, all won by Obama in the 2008 election - Colorado (9 electoral votes), Florida (29), Iowa (6), Nevada (6), New Hampshire (4), Ohio (18), Virginia (13) and Wisconsin (10).
In the last two weeks Romney has moved into a small lead or a virtual tie with Obama in Florida, Colorado, New Hampshire and Virginia, which together account for 55 electoral votes. A sweep of all four still would leave Romney nine electoral votes short of victory - a big reason why the race is boiling down to the battle in Ohio.
A win in Ohio would put Romney over the top and give him some margin of error to lose other states that are still in play. If he does not win Ohio, either Wisconsin or a combination of Nevada and Iowa still could be enough to win, although Obama, in addition to having slim leads in Wisconsin and Iowa, also leads in Nevada.
"Things have moved consistently in Romney's direction, but he still hasn't unlocked the gates to enough places yet," said pollster Thomas Riehle of YouGov, a market research company that is conducting polling in swing states. "Romney needs more good news before he's a safe bet to win."
LOOKING A LOT LIKE 2000, AND 2004
The tightening race has created many different scenarios, including the possibility that the Electoral College winner will not capture the most votes nationwide - similar to what happened in 2000, when Republican George W. Bush got more electoral votes than Democrat Al Gore, who received more of the popular vote.
The prominence of Ohio also has invoked memories of 2004, when Bush won re-election over Democrat John Kerry in the early hours of the morning after Election Day by a margin of less than 120,000 votes in the Midwestern state.
Both candidates are pouring time and resources into Ohio, where Obama has held a steady lead for months and now has an average poll advantage of more than 2 percentage points, according to RealClearPolitics.
HOLDING ON IN THE MIDWEST?
Romney, a wealthy former private equity executive who opposed the Obama-backed federal bailout of the auto industry, has struggled to connect with blue-collar voters in Ohio, where one in eight jobs is tied to the auto industry and the state unemployment rate is lower than the national average of 7.8 percent.
Iowa and Wisconsin, where RealClearPolitics puts Obama's average lead at between two and three percentage points, also have lower state unemployment rates than nationally.
Along with Ohio, they could give the Obama campaign a Midwestern stronghold of 34 electoral votes that protects him against potential losses elsewhere.
"As you look across the country, you are seeing the president is continuing to be very strong in the Midwest in places like Ohio, Iowa, Wisconsin," Obama campaign manager Jim Messina said. "I think we've held our support in the Midwest."
If Obama wins the states where he currently has comfortable leads and adds just those three Midwestern states, he would have 271 electoral votes - enough to be re-elected.
"Until we see something that suggests other states are in play, these Wisconsin, Iowa and Ohio numbers mean it's still a reach for Romney to win," said Lee Miringoff, a Marist College pollster.
He released surveys on Thursday showing Obama with a lead of eight points in Iowa and six points in Wisconsin, although a survey by Public Policy Polling on Friday gave Romney a one-point edge in Iowa.
Romney campaign aides say they are confident that he has enough momentum in Ohio and other swing states to pull out a win, pointing to his growing crowds and improving poll numbers, including those from the campaign's own surveys.
"The dynamic has very much changed in the swing states," said a senior Romney adviser who spoke on condition of anonymity. "The underlying fundamentals in the swing states have changed dramatically in Romney's favor."
In states where Romney has made gains, they have been fueled in part by improvements in his personal favorability ratings, gains with independents and a reduction in Obama's large lead among unmarried women voters.
Romney advisers said the first debate eased the concerns of some voters in swing states who have been bombarded for months by attack ads portraying the Republican as an out-of-touch multimillionaire with little sympathy for the middle class.
"People are getting a lot of information and what they're seeing is very much at odds with the ads that have run," the Romney adviser said. "That has been the biggest impact."
The Obama campaign is counting on what polls show is strong support from the growing Hispanic community to make a difference in Nevada and Colorado, although the level of intensity and voter turnout among Hispanics will be a wild card.
Any gains for Obama among Hispanics could be offset, however, by what polls have found is decreased support among the young and first-time voters who helped sweep Obama to victory over Republican John McCain in 2008.
Most national polls show Obama and Romney deadlocked. A Reuters/Ipsos daily online tracking poll on Saturday gave Obama a 1-point national advantage. Ipsos projects the president will win 315 electoral votes.
In such a close race, any surprise development during the final two weeks could loom large.
Obama and Romney will have their final debate, on foreign policy, on Monday in Boca Raton, Florida, where Romney is once again likely to challenge the president on his handling of the deadly attack on the U.S. consulate in Benghazi, Libya.
The White House on Saturday denied a report by The New York Times that the Obama administration and Iran had agreed to hold one-on-one talks about Iran's nuclear program, another issue that could shape the narrative of the campaign's final days.
Meanwhile, Obama's handling of the struggling economy will again be the focus when the Department of Labor releases the unemployment figures for October on November 2, just four days before the election. The report for September gave Democrats a boost by showing that the nation's unemployment rate was 7.8 percent, down from 8.1 percent in August.
"It was always going to be a really close election," Ipsos pollster Julia Clark said. "But the electoral math still adds up in Obama's favor at the moment."