Receiving benefit payments could jeopardize immigrant citizenship applications

Washington Post:

Trump proposal would penalize immigrants who use tax credits, other benefits

Immigrants who accept almost any form of welfare or public benefit could be denied legal U.S. residency under a plan awaiting approval by the administration, which is seeking to reduce the number of foreigners living in the United States.

I think the idea is that the US is seeking immigrants who would not be a burden on the country and would instead be productive citizens.  Democrats tend to want people who are dependent on the government which tends to vote for them.