Democratic Sen. Sherrod Brown expressed support for a sweeping immigration reform plan unveiled Monday, while GOP Sen. Rob Portman said he wanted to look more closely at the details.

The most contentious element of the proposal — crafted by four Democrats and four Republicans in the Senate — would create a path to citizenship for the estimated 11 million illegal immigrants living in the United States, after meeting certain requirements. The plan also calls for improvements in border security and in tracking immigrants who have overstayed their visas, among other steps.