Poli-Sci Perspective is a weekly Wonkblog feature in which Georgetown University's Dan Hopkins and George Washington University's Danny Hayes and John Sides offer an empirical perspective on the issues dominating Washington. In this edition, Hayes looks at the rhetoric around immigration reform in 2007, and what it can tell us about immigration reform in 2013. For past posts in the series, head here.

Immigration was last in the public eye – at least for more than a few days – from mid-2005 through mid-2007. That period saw the introduction (and eventual failure) of major immigration legislation, several immigration speeches by President George W. Bush, dozens of rallies and protests across the country, the first widely reported activities of the Minutemen, and the deployment of U.S. National Guard troops to the border.

In a working paper, I reported the results of an analysis of every network television news story about immigration reform aired during this two-year period. Supported by the Institute for the Study of the Judiciary, Politics, and the Media at Syracuse University, the project was designed to find out what Americans were hearing about immigration, and who they were hearing it from.

In 284 stories aired on the ABC, CBS, and NBC nightly news shows from May 2005 through June 2007, I identified every argument that was made about immigration – that is, every statement I could identify as advocating for some kind of policy. I organized those 498 arguments into a broader set of “frames,” or arguments with a common theme. Finally, I categorized those frames as pushing for either “restrictive” or “welcoming” policies.

Restrictive frames argued for more limitations on immigration, either by tightening border security, imposing criminal penalties on illegal immigrants, or other methods. A common “restrictive” frame was that immigrants in the United States unlawfully should be treated no differently than other criminals. For instance, Rep. Tom Tancredo (R-Colo.), arguing in 2006 against an immigration proposal that would have created a guest worker program and provided a path to citizenship for some immigrants, said on NBC: “Let’s try enforcing the law.”

Welcoming frames argued for laws that would ease the incorporation of immigrants into American life, such as a path to citizenship, or would allow more workers into the country. A common “welcoming” frame focused on the role immigrants play in the U.S. economy. New York City Mayor Michael Bloomberg said in 2006 CBS story that his city’s economy “would collapse if they were deported.”

Not surprisingly, given the mainstream media’s tendency to present both sides of political debate, the number of restrictive and welcoming frames on the air over this two year period was virtually the same – 52 percent restrictive, 48 percent welcoming.

As shown in red below, the most popular restrictive frames were those in which illegal immigrants were cast as, for instance, “criminals who need to be sent home” or that noted that “these people are law breakers, and don’t deserve to be here.” Combined with those about terrorism and crime – arguments in which specific criminal activity was invoked – law- or security-related themes constituted more than 36 percent of all frames in immigration coverage. Those concerns remain at the heart of the current debate.

The most common frame on the welcoming side, in green, was about the economy. Proponents argued that immigrants constitute an important part of the American economy; imposing new regulations would reduce growth by leaving many jobs unfilled. This made up 15 percent of all frames. The second and third most common arguments suggested that immigrants were just as hardworking as other U.S. residents, or were in the process of pursuing the “American Dream,” a theme that also emerged at Thursday’s Senate Judiciary Committee hearings.

Most striking, however, were differences in who Americans were hearing argue for each kind of proposal. The graph below displays the five most common sources of both types of frames.

On the left, members of Congress and local government officials – mostly, though not exclusively, Republicans – were the chief voices of restrictive policies. Bush, whose reform plan contained numerous border security provisions, also was a prominent advocate. In isolation, those findings are not remarkable; government officials and high-profile political actors are the single most common source of news for the mass media.

But the main source of welcoming arguments was not politicians or government officials at all. Instead, it was immigrants themselves.

In all, nearly one-third (31 percent) of the welcoming frames that appeared on the news were attributed to immigrants or protestors. One reason? About half of all the immigration coverage in this two-year period came during the three months surrounding the massive spring 2006 immigration protests. And while Bush’s arguments for his guest worker program were relatively prominent, relatively few other elected officials were quoted in support of welcoming policies.

Media coverage is but one of many influences on public opinion about immigration. But such a pattern would seem to put proponents of a path to citizenship at a disadvantage.

Sources with higher levels of credibility are more persuasive than less authoritative sources. Despite the fact that many Americans view politicians and government officials with skepticism, people do respond to cues from political elites. There is little evidence, though, that citizens take direction from immigrants or protestors.

That was six years ago, however. And this time around, it appears that things have changed. More elected officials, from both sides of the aisle, seem to be publicly advocating a path to citizenship. To that extent that such arguments make their way to the public through the media, the shift may bode well for supporters of a plan that would allow undocumented workers to remain in the country.

Perceptions of credibility are subject to all kinds of partisan biases, of course. A Washington Post poll this week revealed that telling survey respondents that Obama had proposed a path to citizenship reduced support for the plan by 11 percentage points – 21 points among Republicans, nine among independents. But advocates would probably still rather have the president – or perhaps better still, the junior senator from Florida – making their case than protesters or immigrants themselves.