[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2008/images/10/20/art.johnking.gi.jpg caption="Some McCain insiders believe Colorado is out of reach."](CNN) - The McCain campaign is looking at an Electoral College strategy heading into the final two weeks that has virtually no room for error and depends heavily on a dramatic comeback in Pennsylvania, which hasn't backed a Republican for president in 20 years.
While Iowa, New Mexico and Colorado are still officially listed as McCain target states, two top strategists and advisers tell CNN that the situation in those states looks increasingly bleak. Iowa and New Mexico always have been viewed as difficult races, but the similar assessment of Colorado reflects a dramatic shift for a campaign that had long counted on the state.
"Gone," was the word one top McCain insider used to describe those three states.
This source said while the polls in Colorado remain close, he and most others in the operation were of the opinion that the Obama campaign and its allies have a far superior ground/turnout operation and "most of us have a hard time counting on Colorado."
Campaign manager Rick Davis is among the dissenters, believing the state remains within reach, several sources in and close to the McCain campaign say.
Election Center: Check out the latest state polls
The McCain strategy depends on holding a handful of Bush '04 states that are now rated tossups by CNN: Florida, Ohio, North Carolina, Missouri and Nevada. It also depends on keeping Virginia, which CNN now considers leaning Democratic, in the GOP column.
But even if McCain won all six of those states, in addition to those in which he is already favored, he would still be shy of the 270 electoral votes needed to claim the presidency.
Which is where Pennsylvania and its 21 electoral votes come into play. Most polls show McCain trailing by 10 points or more in the state, but one top adviser told CNN on Monday, "The election hinges on Pennsylvania. We'll win Virginia and Nevada in the end, but lose without Pennsylvania."
President Bush twice heavily targeted Pennsylvania - but both times came up short.
Despite the less than optimistic political assessment of Colorado, McCain at the moment continues to buy television advertising in the state: roughly $700,000 a week the past two weeks with similar spending levels ordered for the week ahead.
Obama is spending a little less than $1 million a week in Colorado.
(One of the McCain sources said that ad spending in Colorado could be increased - even doubled - to somewhere in the ballpark of $1.5 million. "We're not giving up on Colorado," one of the sources said. "But we need to have a math scenario that doesn't count on it.”)
That Obama advantage is also on display in North Carolina, where the Democratic nominee has outspent McCain more than 3 to 1 on television ads.
In the past week, however, McCain essentially matched the Obama levels - $1.1 million to $1.2 million, respectively.
McCain campaign communications director Jill Hazelbaker disputed the sources' accounts.
"We see the race tightening both internally and in public polling," she said. "We are within striking distance in the key battleground states we need to win."
What the sources emphasized was that the campaign needed an alternative to 270 that did not count on Iowa, Nevada and Colorado. They did not say the campaign was ready to pull resources.
The internal discussions reflect the narrow menu of options for McCain.
The sources' sober assessment of Colorado and even more downbeat view of McCains prospects in Nevada come even as GOP vice presidential candidate Sarah Palin campaigns Monday and Tuesday in Colorado and Nevada. From there, Palin moves on to Ohio.