What reason did the american party give in the 1840s to encourage immigration reform

In the 1840s, the American Party, known popularly as the "Know Nothing Party", was against immigration on the grounds that foreigners would take American jobs.  This party wanted to strictly limit, if not eliminate, immigration to the US and were known for their violent opposition to it.  By 1860, this party was essentially extinct, though nativist sentiment can still be found in pockets of American society.

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