Democrats are missing a big opportunity. One of Bill Clinton's most memorable victories was when he joined with Republicans to reform Welfare. Democrats could do the same thing with immigration - join with the President to create a guest worker program that the Republicans oppose.
The gains to the Democrats would be huge. They would cement their relationship with Latino voters which would help them for decades to come and they would drive a wedge between the President and the Republican Congress. The only downside is that anti-immigrant voters might turn against the Democrats. This would not be a big risk. Republicans have already staked out an anti-immigrant position and the pro-immigrant demonstrations have heavy support from Democrat-friendly groups such as organized labor. On the other hand, by not acting they appear weak and indecisive - very Kerry-like.
So why aren't they taking advantage of the opportunity? I'm guessing that their hatred of Bush blinds them from the possibility.
Bush even handed them the chance on a silver plate - complaining over the weekend that Democrats had stopped the immigration reform. Their response was that it was the Republicans' job to pass something.
This fits the Democrats' general model for the past few years. They decided that their role as minority party is to be the opposition party. They don't propose anything. They only oppose.
This is why the Democrats are not gaining in the polls despite a number of Republican mistakes and scandals.