Whether immigration reform would help or hurt the nation's economy is emerging as a key question in the unfolding debate on legalizing millions of undocumented immigrants as the U.S. unemployment rate hovers at around 10 percent.

The answer is hard to pin down because of contradictory conclusions in recently issued reports.

One study released Thursday and endorsed by pro-immigration groups said legalization would boost the economy. But a report issued in December by an organization that seeks tighter immigration controls said less-educated native U.S. workers will find it more difficult to land jobs if illegal foreign workers are given green cards.