White House press secretary Jay Carney made clear Friday that President Obama would not sign an immigration bill unless it was comprehensive, a declaration made days after the president said he was open to a possible piecemeal approach.

"In the end, this has to be comprehensive," Carney told reporters during the daily White House briefing.

“What the president will not sign is piecemeal legislation that only [affects individual provisions],” Obama’s top spokesman added.

House Republicans have said they will not take up the comprehensive immigration bill passed by the Senate in June. Speaker John Boehner, R-Ohio, has said he will only move legislation that has the support of a majority of his caucus and Judiciary Committee Chairman Bob Goodlatte, R-Va., has said he will only move bills piecemeal. GOP leaders pounced on Obama’s most extensive endorsement of the piecemeal approach.

“If they want to chop that thing up into five pieces, as long as all five pieces get done, I don’t care what it looks like as long as it’s actually delivering on those core values that we talk about,” Obama said during a Wall Street Journal forum Tuesday.

The fear among Democrats is that the House would pass border security measures and other elements popular with Republicans, while ignoring a pathway to citizenship for those in the U.S. illegally — often dismissed by critics as a form of amnesty.

Trying to pressure Republicans to act on the Senate bill, Vice President Biden visited the National Mall on Friday to meet with advocates fasting to protest the House's decision not to take up the immigration reform legislation.

Republicans argue that Democrats are trying to ram through big government legislation before conservatives can fully study the consequences. GOP leaders point to Obamacare as the model for what they want to avoid.

Carney bristled at that critique Friday.

“I don’t think that anybody would argue,” he said, that “immigration reform is being rushed here.”