Philbin stepped down from hosting duties on syndicated show Live! With Regis and Kelly earlier this month (Nov11) after 28 years.
A new co-anchor for Ripa has yet to be announced, and Harris is American TV pundits' favourite to take up Philbin's empty seat.
But the star is adamant his commitments to TV comedy How I Met Your Mother for the next 18 months will prevent him from signing a deal.
He tells the New York Daily News, "I'm a huge Kelly Ripa fan. But it's on a competing network (to How I Met Your Mother) and I have a contractual obligation for at least another year and a half, and I can't imagine she'd want to fly solo for that long."