A Senate committee is scheduled to begin debating amendments on a comprehensive immigration reform bill this week and already the rhetoric around the hot-button issue is heating up.

A coalition of liberal advocates was out with a statement Monday calling opponents to the proposal the “Gang of Hate,” a play off the nickname of the “Gang of Eight” bipartisan group of senators that developed the legislation.

(David J. Phillip/AP) Sen. Ted Cruz (R-Texas) (David J. Phillip/AP)

America’s Voice, a leading immigration advocacy group, listed Republican Sens. Jeff Sessions (Ala.), Chuck Grassley (Iowa), John Cornyn (Tex.), Ted Cruz (Tex.), and David Vitter (La.) in the group of haters, saying they have embraced an anti-immigration strategy that “drove the GOP to the brink of the demographic cliff and put them in the position they are in today.”

But the characterization drew immediate umbrage from one of the GOP senators that America’s Voice is counting on to see the immigration fight through Congress. Sen. Marco Rubio (R-Fla.) wrote on his Twitter account that the attack on the senators is a “disgrace.”

“I disgree with them on parts of #immigrationreform but they are not haters,” wrote Rubio, a member of the bipartisan group that developed the bill.

Rubio is in a tricky position as a tea-party favorite who has championed the immigration proposal. Pro-immigration advocates hope he can sell the details, including a 13-year path to citizenship for up to 11 million illegal immigrants, to the GOP’s conservative wing.

Conservatives opposed to immigration reform have cited security concerns, as well as the potential costs of allowing illegal immigrants to pursue citizenship. The Heritage Foundation released a study Monday that estimates the Senate proposal would ultimately cost $6.3 trillion in health care and social services  for the millions of immigrants who become citizens. Such estimates have been disputed by other organizations that cite fees and increased taxes paid by undocumented workers who earn legal status.

Rubio has called for additional hearings and more time to amend the bill, saying he welcomes ideas from fellow Republicans on ways to improve it. He has said the border security components likely will need to be strengthened for the legislation to have a change to pass the Senate and House.

Senate Judiciary Committee Chairman Patrick Leahy (D-Vt.) has set a deadline of Tuesday for amendments to be filed, and the “markup” process of the bill will begin Thursday.