[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2008/POLITICS/10/29/poll.wednesday/art.obamageneric.gi.jpg caption="New gains for Obama on the CNN Electoral Map."](CNN) - If Barack Obama is betting on Nevada, he may find a pleasant payoff. A new poll suggests that the Democratic presidential candidate is widening his lead there.
That's contributing to an increase in territory for Obama in CNN's Electoral College Map. The map estimates what would occur if the election were held today, by reviewing state polls, voting trends, campaign visits and advertising.
In the Nevada survey - one of five CNN/Time/Opinion Research Corporation state polls released Thursday morning - 52 percent of likely voters say Obama is their choice for president, with 45 percent backing John McCain. That seven-point lead is up from a five-point advantage Obama held in a poll taken one week ago.
Nevada narrowly voted for George W. Bush in the last two presidential contests.
"Obama is racking up support among blue collar voters in Nevada," said CNN Polling Director Keating Holland. "Two weeks ago, he had a six-point lead among people with no college degree. Now he has a 23-point lead over McCain among that group. If the unions are making a big push for Obama in Nevada, it seems to be working."
The new numbers in Nevada, along with similar findings from other new polls in the state, are factors that led CNN to move Nevada and its five electoral votes from a "toss-up" state to "lean Obama" in its new Electoral College Map.
With that change, CNN estimates that if the election were held today, Obama would win 291 electoral votes compared with 163 for McCain; another 84 electoral votes are up for grabs.
A candidate needs 270 electoral votes to win the presidency.
On Wednesday, CNN switched Colorado and its nine electoral votes from "toss up" to "lean Obama," thanks to a number of new polls, including a CNN/Time/ORC poll that suggests Obama has an eight-point lead in Colorado.
CNN also changed Indiana, which has 11 electoral votes, from "lean McCain" to "toss up." A new CNN Poll of Polls suggests McCain holds a two-point lead over Obama in Indiana, which hasn't voted for a Democrat in a presidential election since 1964.
The Poll of Polls is an average of the latest state surveys.
The state of Washington was also moved from "lean Obama" to "safe Obama," though that move doesn't change the electoral count.
With the prospect of losing some of the states that President Bush won four years ago, McCain, R-Arizona, has his eyes on Pennsylvania and its 21 electoral votes.
McCain and his running mate, Alaska Governor Sarah Palin, and surrogates are spending a lot of time campaigning in the state. McCain hopes to become the first Republican presidential candidate to win the state since 1988.
A new poll, however, suggests that McCain's efforts may not be paying off.
Fifty-five percent of likely voters in Pennsylvania say they are backing Senator Obama, D-Illinois, with 43 percent supporting McCain. That 12-point lead for Obama is up from a nine-point advantage he held in CNN's last poll in the state, conducted last month.
"Pennsylvania is the keystone to McCain's electoral college strategy, but he faces a tough task," said Holland. "Obama has an edge in Philadelphia, of course, but also in the Philly suburbs, and he's ahead by six points in the western part of the state."
Another state McCain needs to keep in the Republican camp is Ohio, where 20 electoral votes are up for grabs. The new poll indicates Obama holds a small four-point lead, 51 percent to 47 percent. Both campaigns are spending a lot of time and money in Ohio in this last week before the election.
It's a simliar story in North Carolina, which last voted for a Democratic presidential candidate in 1976, when Jimmy Carter was running. A new poll suggests Obama has a six-point lead over McCain, 52 percent to 46 percent.
Obama was up by four points in our last poll, conducted last week.
"Other polls are showing North Carolina is essentially tied, but our poll shows Obama picking up support among younger voters and the blue-collar segment. Those are two reasons the race in North Carolina has gone from a 49-49 tie in early October to a 52-46 edge for Obama, at least in our results," Holland said.
The poll indicates McCain holds a small lead in his home state of Arizona - 53 percent to 46 percent. Another poll released this week suggests the race is closer in Arizona, which McCain has represented in Congress for 26 years.
The poll was also expanded to include the major third party candidates, Independent Ralph Nader, Libertarian candidate Bob Barr, and Green Party candidate Cynthia McKinney.
None of them are polling over 3 percent in any of the states surveyed, and none seem to be a factor in the outcome of the results in those five states - other than Ohio, where Nader's 3 percent showing could have an impact.
The CNN/Time/Opinion Research Corporation poll was conducted Thursday through Tuesday. It surveyed 807 likely voters in Arizona, 684 likely voters in Nevada, 667 likely voters in North Carolina, 779 likely voters in Ohio, and 768 likely voters in Pennsylvania.
The survey's sampling error is plus or minus 3.5 percentage points in Arizona, Ohio and Pennsylvania and plus or minus 4 percentage points in Nevada and North Carolina.