A Senate proposal for immigration limits backed by President Donald Trump would hurt family unity and exclude too many vulnerable people, the U.S. Catholic bishops have said.

"Had this discriminatory legislation been in place generations ago, many of the very people who built and defended this nation would have been excluded," said Bishop Joe S. Vasquez of Austin, the chairman of the U.S. bishops' Committee on Migration.

Bishop Vasquez voiced strong opposition to the legislation introduced by Sens. Tom Cotton (R-Ark.) and David Perdue (R-Ga.). The proposed bill is called the Reforming American Immigration for a Strong Economy Act, also known as the RAISE Act.

The legislation announced on Wednesday would cut by half the number of legal immigrants the U.S. accepts each year. It would limit green cards for foreign nationals seeking to reunite with their families, and halve the number of refugees allowed to enter the country. The diversity visa lottery, which gives visas to countries with low rates of immigration to the U.S., would also be eliminated, National Public Radio reports.

"The United States supports families and should not throw up obstacles to their unity," Bishop Vasquez said Aug. 2, charging that the legislation "would have our nation turn its back on this long and storied tradition of welcoming families setting out to build a better life."

The bishops objected to the permanent cap on the number of refugees who are allowed safe passage through the country, saying this would prevent the flexibility needed to respond to humanitarian crises.

"As a Church, we believe the stronger the bonds of family, the greater a person's chance of succeeding in life. The RAISE Act imposes a definition of family that would weaken those bonds," Bishop Vasquez said.

The bishops urged the Senate to reject the measure and asked Congress and the president to enact comprehensive immigration reform.

"I believe that such reform must recognize the many contributions that immigrants of all backgrounds have made to our nation, and must protect the lives and dignity of all, including the most vulnerable," said Bishop Vasquez.

President Donald Trump said the bill would reduce poverty, increase wages, and save "billions and billions of dollars" in taxpayer money. The bill would bar new arrivals from receiving welfare.

The president said the proposal would favor applicants "who can speak English, financially support themselves and their families, and demonstrate skills that will contribute to our economy."

The prospects for the bill's success are not clear and at least two Republican senators are likely opponents, National Public Radio reports.