After decades of pushing for reform, there's hope that 2014 may very well be the year that comprehensive immigration legislation will make substantial progress.

A new study shows that up to 6.5 million undocumented immigrants currently living in the United States could eventually become citizens under proposals being discussed by House Republicans.

According to a report recently published by the National Foundation for American Policy, a nonpartisan research group in Washington, between 4.4 million and 6.5 million unauthorized immigrants could gain an eventual pathway to citizenship based on policy ideas that have been put forward by Republican Rep. Robert Goodlatte. According to Speaker John Boehner, Goodlatte's principles will guide House action on this issue this year, reports the New York Times.

Goodlatte, the chairman of the House Judiciary Committee, and other GOP leaders have adamantly opposed legislation that includes a "special" or direct pathway to citizenship for immigrants residing in the country without legal papers. They also refuse to support the sweeping bipartisan bill that the Senate passed over the summer which includes a 13-year path to citizenship. 

Instead, House GOP have backed taking a piecemeal approach to tackle immigration reform. Goodlatte is offering a plan that would provide provisional legal status to undocumented immigrants, then allow those who can demonstrate they are eligible to apply for permanent residency or a green card through the existing system through sponsorship by a family member or employer.

Based on the foundation's report, 3.1 to 4.4 million immigrants would be eligible for green cards since they are parents of American citizens, even without major changes to current immigration law. As many as 600,000 could gain permanent residency status as spouses of citizens and legal residents, and up to 45,000 could receive green cards within two decades as low-skilled workers.

The estimate assumes the House would pass legislation creating new green cards for "DREAMers," young undocumented immigrants who entered the nation as children. The organization's executive director Struart Anderson calculates that 800,000 to 1.5 million of those immigrants would gain a pathway to citizenship.

Under the foundation's projection, at least 2 million immigrants would have to wait as long as two decades before they could apply for naturalization, while up to 5 million immigrants would remain here with legal status but no prospect of becoming citizens.

Tamar Jacoby, the president of ImmigrationWorks USA, said on Tuesday that proposals for a bill with no separate path to citizenship for most illegal immigrants were gaining ground among House Republicans, reports the Times.