Senate restriction passed almost unopposed, split only over severity.

Evidence

The Dillingham bill passed the Senate with practically no opposition except from southern and western Senators who wanted complete suspension. The House of Representatives then abandoned its suspension plan in favor of the quota system but persuaded the Senate to reduce the quotas from 5 per cent to 3 per cent of the 1910 census. This would restrict European immigration to a maximum of about 350,000 and assign most of that total to northwestern Europe. — John Higham, Strangers in the Land, 1876