Mr. Connerly said Mr. Obama's organization mobilized unprecedented numbers of Democrats who blocked his bid to add Colorado to four states that have banned affirmative action.
"Colorado essentially went blue this time around, but we still drew over a million votes," Mr. Connerly, a black businessman and former University of California regent, told The Washington Times. "I'm very heartened by this. I'm just sorry we got caught up in the Obama phenomenon."
Once a solidly Republican red state, Colorado went blue this year as voters backed Mr. Obama over Republican John McCain by a margin of 53 percent to 47 percent. The Obama campaign targeted Colorado early on as a potential flip state and invested heavily in voter-registration and get-out-the-vote efforts.
Mr. Connerly's Sacramento-based American Civil Rights Institute did succeed in Nebraska on Tuesday, where an anti-preferences measure overcame efforts by such Nebraska heavyweights as investor Warren Buffet to defeat it - joining California, Michigan and Washington with such bans.
Another factor working against the Colorado measure was the size of the state ballot. Colorado boasted the longest ballot in the nation, with 14 initiatives, including 10 proposed constitutional amendments.
All but four of the measures failed in what some analysts described as a "forget about it" reaction by overwhelmed voters. Two of the initiatives that did pass were standard housekeeping proposals aimed at cleaning out obsolete state laws.
"We got caught up in those two factors," Mr. Connerly said. "If the election were held tomorrow and there were no Obama on the ticket, and you didn't have people telling voters to 'just say no' to all the initiatives, we'd win by 18 points."
Indeed, Amendment 46 was polling at more than 60 percent just two weeks ago.
But the results show that Colorado "stands for a different set of values than this initiative," said Melissa Hart, the University of Colorado law professor who co-chaired the anti-Amendment 46 campaign.
She agreed that the Obama candidacy affected the outcome, but that didn't make the defeat of Amendment 46 any less legitimate.
"I think it's true that the Obama campaign brought out a lot of new Colorado voters, and when voters of all ilks took a look at [the amendment], they said, 'We don't want this in our constitution,'" Ms. Hart said. "Obama voters are still Colorado voters, and that's what they think."
The anti-46 campaign also benefited from the support of Democratic Gov. Bill Ritter and Denver Mayor John Hickenlooper. Ads had warned voters against amending the constitution at the behest of a California-based group.
"I'm really proud of the voters of my state," Ms. Hart said. "We went door to door, voter to voter, telling people not to fall for the deception, and they didn't."
With several thousand provisional ballots still uncounted, Amendment 46 was failing by a margin of about 50.5 to 49.5 percent. The campaign had not officially conceded yesterday, but was getting close to that point, said Colorado co-chairperson Jessica Peck Corry.
Foes of affirmative action had some cause for celebration. In Nebraska, voters approved Initiative 424, an anti-preferences measure identical to the Colorado amendment, by a margin of 58 percent to 42 percent.
"You didn't have the far left really going all out for Obama and working to defeat us" in Nebraska, Mr. Connerly said.
The group had originally planned a "Super Tuesday for Civil Rights" with proposals in five states, but was only able to qualify for the Colorado and Nebraska ballots.