Would liberals be supporting amnesty if all the illegals were white and from eastern Europe?

No. Check this out -
"Mainly, though, they marvel at the bipartisan muscle and positive spin the illegal Irish can still muster, even as their numbers dwindle to perhaps 25,000 to 50,000 across the country — those left behind by a tide of return migration to a now-prosperous Ireland." Yes, illegal Irish. Amazingly, they get very little attention. Maybe it's because they don't whine and feel "entitlement" like the illegals from Mexico do.

liberals only want power at any cost