From NPR:

WELNA: What’s more, majority leader Frist is backpedaling from his initial support for the Senate compromise, which allows those who’ve been in the country illegally at least five years, to pursue citizenship. Frist, who’s made it clear he’d like to be the next president, told NPR the bill goes too far, and amounts to an amnesty.
Sen. FRIST: When we bring it back, there will be amendments to modify–in the temporary worker program, and probably in the 12-15 million people who are coming out of the shadows–to pull back on the amnesty provisions. I would pull back on the amnesty provisions and will support those amendments.

See here.