Vice President Joe Biden warned Monday that Donald Trump's approach to immigration goes against long-held U.S. values, and blasted Trump's "constant stream of inflammatory rhetoric against immigrants."

"These responses tarnish our most closely-held values and ignore our cherished history as a nation of immigrants where the poor and vulnerable have a fair shot to achieve the American dream," Biden wrote in an op-ed on Univision News' website.

Biden said he planned later in the day to try a more cooperative approach in a meeting with Costa Rica President Luis Gillermo Solis, where they will discuss the recent flood of immigration from Central America across the southwestern U.S. border. Biden said he would use that meeting to discuss "our next steps, in cooperation with the United Nations, to help vulnerable families and individuals in the region."

The Trump campaign signaled Sunday that it could change its tune and withdraw its call for the mass deportation of 11 million illegal immigrants after insisting for more than a year that the undocumented migrants would "have to go."

But Democrats are skeptical, and the Obama administration has taken a "fundamentally different approach" to trying to halt the flow of thousands of unaccompanied minors from Central America, Biden wrote.

The Obama administration has faced some criticism from the left, from those who say President Obama has deported more migrants than any U.S. president in history. But Biden didn't address that, and instead he focused on the positive and efforts to work with Central America to stem the migrant tide.

After the flow of people spiked in the summer of 2014 and Obama put him in charge of leading the U.S. response, Biden said he has traveled to Costa Rica, Honduras and three times to Guatemala to work with leaders there to cooperate on solutions and come up with incentives for families to remain there, instead of fleeing poverty and "endemic violence" in those countries.

The administration, he wrote, has taken a two-track approach — providing relief to immigrants in immediate danger, while trying to pursue long-term solutions to address the underlying "drivers" of migration.

"Ultimately, we want the people of Central America to have a future of hope and prosperity in their own countries. But those suffering under terrible violence today cannot wait for fundamental change," he said, noting that the administration has made it easier for Central American migrants to qualify for U.S. refugee and resettlement programs.

Biden said the U.S. also is working with other regional partners like Mexico to treat immigrants humanely, and ensure that steps to limit illegal immigration "respect the human dignity of migrants and give full consideration to their refugee claims under the law."

In addition, he wrote, the U.S. has increased foreign assistance to Central America over the past two years, more than doubling the budget for the region from $317 million in 2014 to $750 million this fiscal year.

The money is not a "gift," Biden stressed. In order to receive the money, the countries must meet certain benchmarks for strengthening security and "implementing political and economic reforms," and make anti-corruption efforts.

"I have personally challenged the presidents [of] El Salvador, Honduras and Guatemala to honor their commitments to us and, more importantly, to their own people," Biden wrote. "To their credit, they created the Alliance for Prosperity to coordinate their own efforts, and they've put up $2.6 billion of their own money to match our financial commitment to the region.

"Central America still has along way to go," he wrote. "But progress is possible with continued political will on all side."

"... The people of Central America are eager to seize this moment of opportunity to achieve lasting change. And the United States will continue to work with all of our partners in the region and support their progress to make Central America the next great success story of the Western Hemisphere."