Democrats revised a plan nixed by parliamentarian Elizabeth MacDonough earlier this month by changing the eligibility date from 1972 to 2010, thereby reducing the number of undocumented immigrants who would be eligible for permanent residency from 8 million to 6.7 million, the report said.
But MacDonough told Democrats that the second plan was a non-starter, according to a copy of the guidance obtained by newspaper.
Changing the registry date is a "weighty policy change and our analysis of this issue is thus largely the same" as Democrats' previous proposal, MacDonough told Democrats in her guidance.
Legal US permanent residents are eligible to apply for citizenship after a waiting period.
Meanwhile, Democrats are pursuing other back-up plans with the Senate referee, an unnamed source familiar with the strategy said in the report.