Mexico President Andrés Manuel López Obrador announced Monday that he is skipping this week’s Ninth Summit of the Americas, a blow to President Joe Biden as he tries to unite the region to address migration.

“There cannot be a summit if all countries are not invited,” López Obrador said at a press conference Monday after the United States refused to invite Cuba, Nicaragua, and Venezuela to the summit.

He said Mexico’s foreign affairs secretary, Marcelo Ebrard, will attend the summit instead. López Obrador said he will meet with Biden in July.

López Obrador has been threatening to boycott the summit if the United States didn’t invite every country in the region, including the autocratic leaders of Cuba, Nicaragua, and Venezuela.

The Biden administration said they do not want to invite countries that have not upheld democratic principles.

López Obrador’s absence is likely to be seen as a snub to Biden as the U.S. prepares to host the summit for the first time since its inception in 1994. The summit is scheduled to begin Wednesday.

The White House has said climate change, COVID-19, and the economy are going to be among some of the issues discussed.

But a priority for the administration is migration. The United States has seen record levels of migrants coming to the U.S.-Mexico border over the past year. In April, the United States saw a record number of border encounters for that month in more than two decades.

The Biden administration has tried to work with key countries in the region, including Mexico, Honduras, Guatemala, and El Salvador, to address the root causes of migration.

López Obrador might not be the only key official who is skipping out on the summit.

Newly-elected Honduras President Xiomara Castro previously indicated that she would not attend the summit if some countries were excluded from the event.

Sen. Bob Menendez, D-N.J., criticized López Obrador’s decision to skip out on the summit, saying it “will, unfortunately, set back efforts to continue repairing the relationship and to cooperate on issues pertinent to the well-being of both our nations.”

Menendez said the Mexican leader is standing “dictators and despots over representing the interests of the Mexican people in a summit with his partners from across the hemisphere.”