Senator John McCain (R - AZ) told a town hall meeting in Mesa, Arizona that he remains "guardedly optimistic" that the House of Representatives will pass immigration reform this year.

"I don't accept your premise that the House of Representatives will absolutely reject a path to citizenship," McCain told a reporter at the forum, according to MSNBC. "I think we'll know more in two or three months."

Sen. McCain co-sponsored the Border Security, Economic Opportunity, and Immigration Modernization Act of 2013 with Democrats and Republicans alike, a bi-partisan effort referred to as the "Gang of Eight". That legislation went through the Senate by a vote of 68 to 32.  That bill would create a pathway to citizenship for illegal immigrants, a measure that many in the far-right wing of the Republican caucus oppose.

Currently, there are 11 million illegal immigrants in the United States, or approximately 3.5 percent of the country's population of 319 million.

All four Republican senators involved in the immigration bill have increased their national spotlight with the legislation's passing, to both positive and negative effect. McCain has thrust himself back into the national conversation after receding briefly following his failed 2008 presidential bid.  Sen. Marco Rubio (R - FL) is an early frontrunner in the race for the party's nomination for the presidency in 2016.  Rubio has urged his House colleagues to pass the bill, threatening that President Obama may choose to simply force immigration reform by executive order, thereby cutting Republicans out of the discussion.

Sen. Lindsay Graham (R - SC) has, meanwhile, brought upon himself the unwelcome attention of tea party activists and extreme right-wingers, who will attempt to force the long-serving senator out of office in the state's primary. So far, three challengers have stepped forward to challenge Graham in his home state: sate Sen. Lee Bright, perennial candidate Richard Cash, and Nancy Mace.