The RCP Average for Colorado gives Obama a 5.5-point lead -- good, but not quite commanding yet. The problem for McCain is that -- with the Obama campaign's major cash advantage -- he's got to choose carefully where he competes. In that vein, Jonathan Martin has this update on the McCain campaign's CO effort:

Two senior aides didn't deny that Colorado appeared challenging, but pointed to the two key indicators of any campaign's intent, time and money, to make the case that they were still holding out hopethere.

"We didn't send Gov. Palin there for no reason," said one, a reference to the vice presidential nominee's three rallies across the state today.

Another aide pointed out that the campaign and RNC's independent expenditure committee were both still on the airwaves there

"The combined reported spending of the RNC IE and the campaign is very similar, we trail by very small margins (around $500,000) ."

But McCain aides avoided making firm commitments about Colorado, careful to avoid portraying any state as a must-win.

With 9 EV, Colorado isn't as important for McCain as, say, Virginia or Florida. But it could have a decisive impact on election night if McCain is able to hold on to some states where he now trails.