By ALAN FRAM
WASHINGTON (AP) — Senate Democrats are launching an uphill fight to rescue their drive to help millions of immigrants remain legally in the U.S. But their pathway is unclear. And the uncertainty is exposing tensions between party leaders and progressive groups demanding bold results. Their move comes a day after the Senate parliamentarian said Democrats’ sweeping proposal must fall from a $3.5 trillion measure that’s shielded against bill-killing Republican filibusters. Lawmakers and advocacy organizations say they are already weighing fresh alternatives in hopes that the nonpartisan parliamentarian, Elizabeth MacDonough, would accept them. But it seemed strongly likely that Democrats might have to winnow their push to more modest legislation.