A moderate Republican senator heaped praise on Tuesday on President Barack Obama's Supreme Court nominee, bucking Senate Republican leaders in calling for confirmation hearings but saying she was not optimistic enough others in her party would agree.

Susan Collins of Maine became only the second Republican senator to meet with Merrick Garland since Obama nominated the centrist appellate judge last month to fill the court's vacancy left by the Feb. 13 death of Justice Antonin Scalia.

At a time when Republican senators are coming under increasing pressure from conservative activists to go along with Senate Majority Leader Mitch McConnell's plan to block any nominee chosen by Obama, Collins met for an hour with Garland.