The Democratic-led U.S. Senate on Wednesday rejected a Republican amendment that foes said would have undermined a key element of the White House-backed immigration bill, a pathway to citizenship for 11 million undocumented immigrants.

Republican Senator Charles Grassley of Iowa said the defeat of his amendment, 57-43, broke a promise by President Barack Obama's Democrats to permit an "open debate" on the landmark legislation. Democrats forced a vote after little discussion. (Reporting by Thomas Ferraro and Richard Cowan; Editing by Vicki Allen)