Sen. Marco Rubio cast doubt on the prospects for immigration reform passing Congress this year, despite a renewed effort by House Republicans to address the issue.

The Florida Republican, a possible 2016 presidential candidate, was a key negotiator of the bipartisan immigration reform legislation that cleared the Senate in June. But Rubio said a deep lack of trust in President Obama to uphold the border security measures likely to be included in any final deal stands in the way of attracting the Republican votes needed to send a bill to the White House.