While Fox News primetime viewership has been on the decline in recent months, it remains a highly-profitable network with the largest news audience on cable. Its median prime-time viewership was 1.9 million in 2011, according to the Pew Research Center, well ahead of MSNBC (773,000) and CNN (654,000).
Still, many advocates caution against overstating the influence of Fox, insisting the network will not play a decisive role in the immigration debate one way or the other.
"Talking heads are talking heads. Whatever they say is fine," said Jenks of Numbers USA, which opposes the Obama and Senate plans. "If we had relied on any of the mainstream media in 2007, that bill would have passed. We don't have any intention of relying on them this time."
Ali Noorani, executive director of the National Immigration Forum, says the diversity and bipartisanship of advocates for a reform plan -- including pathway to citizenship -- will override any single, particular influence.
"I think that Fox having the role as a conservative media outlet now, frankly, has in its Rolodex a range of conservative speakers to this issue, whether it's Sen. Marco Rubio; Leith Anderson, president of the National Association of Evangelicals; Richard Land, the head of Southern Baptist Convention -- these are conservative leaders who can speak to conservatives who want to see this country move forward with a broad immigration reform," Noorani said.
Murdoch has tried to downplay his network's influence on political debate over immigration, too.
"We are home to all views on Fox," he told the congressional panel in 2010. "We don't censor that or take any particular line at all. We are not anti-immigrant on Fox News."