During a House floor speech, Rep. Steve King, R-Iowa, expressed frustration that one of his conservative heroes, President Ronald Reagan, had signed the Immigration Reform and Control Act, a 1986 law that gave legal status to many illegal immigrants who were then residing in the United States. King is a leading congressional critic of efforts to legalize undocumented immigrants.

"Ronald Reagan’s signature on the 1986 amnesty act brought about Barack Obama’s election," King said in the May 23, 2013, speech.

King’s point was that a side effect of the 1986 law was to boost the numbers of Hispanic voters -- so many Hispanics were made legal by the law, he argues, that the number exceeded Obama’s margin of victory.

In his speech, King didn’t say explicitly whether he meant Obama’s initial victory in 2008 or his 2012 re-election, but he did refer to the election in which Hispanics supported Obama by a 71 percent margin, which was the percentage in 2012. So we will look at the 2012 contest. In addition, we will look at Obama’s raw-vote margin, since King didn’t mention in his speech that he was referring to Obama’s margin in the Electoral College, and his office didn’t offer that as an argument when we conferred with them as we reported this story.

King laid out a clear mathematical roadmap in his speech.

King said that 3 million people "received amnesty" under the 1986 law. To that number, he added an additional five people for each newly legalized person, to reflect those legalized under family reunification policies. That means an additional 15 million people. If 71 percent of the combined 18 million Americans voted for Obama, King argued, then Obama benefited from nearly 13 million votes due to the act -- a number that’s a lot bigger than his margin over Mitt Romney of 4.7 million votes. The gap is large enough to cushion any decline due to deaths and departures among 1986 amnesty recipients, something King suggested was a reasonable adjustment to make.

"Ronald Reagan’s signature on the 1986 amnesty act brought about Barack Obama’s election," King said. "If ... we take 15 million people out of the rolls and say they wouldn’t have been here without the 1986 amnesty act, or at least they wouldn’t be voting, and if 71 percent of them voted for Barack Obama, then it’s clear to anybody that can do any kind of statistical analysis that Barack Obama wouldn’t be President of the United States without Ronald Reagan’s 1986 amnesty act."

So, case closed? No.

After sifting the data and checking with experts in immigration, demography and voting, we find King’s estimate too high.

This is an oversimplification on several fronts. For starters, King didn’t account for the fact that many of the newly legal residents did not become citizens, and thus never earned the right to cast a vote. He also didn’t account for the low rates of voting participation among Hispanics who do have the right to vote. And most important, King’s estimate of five family members receiving legal status for every case of amnesty under the 1986 law is wildly high.

Here’s our best attempt at a calculation:

• The best estimates show that 2.7 million people received permanent residency in the United States as a result of the 1986 law. That’s slightly lower than the number King settled on, but not dramatically so.

• It’s trickier to determine how many additional people these 2.7 million immigrants brought in through family provisions, but with expert assistance, we made some estimates. The best time span to look at is 1992 to 2012, since 1992 is when the immigrants legalized due to the 1986 law would have had their first opportunity to bring in relatives.

According to Department of Homeland Security statistics, 12.2 million immigrants were given permanent legal status between 1992 and 2012 for family reasons. So right off the bat, King can’t possibly be right that the 1986 law led to 15 million family members being made legal.

Moreover, it’s extremely unlikely that anything approaching 12.2 million family members were made legal as a result of the 1986 act, since legalizations from the 1986 act account for a small percentage of all legalizations since 1992. Specifically, the U.S. added 19 million new legal permanent residents between 1992 and 2012, of which 2.7 million -- or just 14 percent -- were made under the 1986 act.

It’s hard to know whether 14 percent is the right number to use in our estimate, but it seems to be a reasonable starting point. And 14 percent of the 12.2 million family-related legalizations works out to 1.71 million stemming from the 1986 law.

This means that every person who got amnesty from the 1986 law didn’t secure legal status for five more people, as King said. On average, each of them secured legal status for less than one additional person.

A spokeswoman for King provided us with a study by the Center for Immigration Studies, a group that opposes looser rules for immigration, that expresses skepticism about the design and consequences of the 1986 law. However, this group estimated that only 743,000 people became legal for family reasons after the 1986 law -- an amount substantially lower than our estimate.

So, using our estimate, here’s the subtotal so far: If you add 2.7 million and 1.71 million, you get 4.41 million additional permanent residents due to the 1986 law.

• About 90 percent of immigrants legalized by the 1986 law were Hispanic.

Subtotal: About 4 million of the newly legalized immigrants were Hispanic.

• Only about 45 percent of those legalized by the 1986 law had become U.S. citizens by 2009. It’s now a few years later, so we’ll assume that by 2012 that rate has grown to 50 percent:

Subtotal: About 2 million of the newly legalized immigrants were Hispanic and eligible to vote.

• Some of the immigrants legalized by the 1986 law died in the interim. There are no good estimates for this factor, but normal death rates over a 20-year period would suggest perhaps a 10 percent decline due to death since the first amnesties were granted.

Subtotal: 1.8 million of the newly legalized immigrants were Hispanic, eligible to vote, alive and living in the United States.

• Among Hispanic citizens at least 18 years of age, only about 48 percent voted in 2012.

Subtotal: 864,000 newly legalized immigrants who were Hispanic and eligible to vote actually did vote.

• Hispanics voted for Obama at a 71 percent rate in 2012.

Total: Using these calculations, we estimate that 613,440 Hispanic immigrants legalized due to the 1986 law voted for Obama in 2012. That’s far less than Obama’s 4.7 million vote margin that year. In fact, this sliver of the electorate counted for just 13 percent of Obama’s margin of victory.

Just to be certain, we also did an alternative calculation. This calculation shows an even lower number.

According to the Census Bureau, 3.1 million Hispanic voters in 2012 were immigrants. Let’s assume, using our number from above, that 14 percent of them (or 434,000) were legalized by the 1986 act. If 71 percent voted for Obama, then he would have received about 308,000 votes as a result of the 1986 act. This is even further below King’s estimate.

In a statement to PolitiFact, King's office said, "My point all along has been that Republicans should not be fooled into thinking that enacting another, much larger, amnesty will help advance the Republican Party. Open-borders Republicans can not disagree with my analysis of the 2012 election results because if they do they are refuting their own argument that the Hispanic vote is key."

Our ruling

King said that when Reagan signed the 1986 act, he prompted such a growth in the Hispanic electorate that it accounted for Obama’s margin of victory in 2012.

It’s no secret that long-term growth in the Hispanic population -- stemming from overall immigration policies, higher birth rates and other factors -- has aided Obama’s electoral prospects. However, very little of this growth stems from the law Reagan signed, and King’s estimate of the number of family members indirectly legalized by the law is far too high. The actual impact from the 1986 act is far more modest, adding potentially between 300,000 and 600,000 votes for Obama, rather than 4.7 million. We rate King’s claim False.