The House of Representatives has launched an impeachment inquiry into whether Joe Biden, while serving as vice president, abused the powers of his office to enrich and protect his dissolute son and himself. But if Republicans are going to pursue such a step, they might have stronger grounds in focusing not only on Biden’s vice presidential deeds but also on his refusal, as president, to exercise his own powers and responsibilities—namely, by failing to enforce federal immigration laws.

A president’s most basic obligation is to enforce, or execute, federal laws as written and passed by Congress. The opening line of Article II of the Constitution declares, “The executive Power shall be vested in a President of the United States of America.” The essence of executive power is the authority—and the corresponding responsibility—to carry out the laws. If any more clarity were needed, the Constitution also states that the president “shall take Care that the Laws be faithfully executed.” The current immigration crisis is largely a product of Biden’s refusal to fulfill his core constitutional duty to enforce federal laws.

Under Biden’s presidency, illegal aliens are often willingly turning themselves in to the authorities under the guise of seeking asylum, even though from fiscal year (FY) 2008 through FY 2019, only 14 percent of those claiming a credible fear were actually granted asylum. In the words of Raul Ortiz, whom the Biden administration selected as U.S. Border Patrol (USBP) chief, aliens are likely “turning themselves in because they think they’re going to be released” into the United States. This awareness of the likelihood of being released has brought a flood of illegal aliens to the American border, a flood that won’t be significantly affected by Biden’s recently announced change of heart on building a few miles of border wall.

Indeed, the cause of the current migrant crisis is Biden’s refusal to detain illegal aliens as the law requires. In the words of U.S. District Court Judge T. Kent Wetherell, that refusal is “akin to posting a flashing ‘Come In, We’re Open’ sign on the southern border.” Aliens—and cartels—can hardly miss this signal, and so they have come to the border in huge numbers. Calculations by the American Main Street Initiative (where I am president), based upon U.S. Customs and Border Protection statistics, reveal that in just two and a half years under Biden, 1 million more encounters with noncitizens at the southwest border have taken place than in the prior eight years combined under Presidents Obama and Trump.