The Senate cleared the 60-vote threshold to begin debate on a GOP priority, with Democrats backing it as the party recalibrates politically on immigration. Final passage is still uncertain.

The measure easily cleared the 60-vote filibuster but marked the first of likely several procedural hurdles before Republicans can declare victory.

A significant number of Senate Democrats voted with Republicans on Thursday to advance a GOP-led bill to require the detention of undocumented migrants charged with certain crimes – a key step that puts the legislation on the verge of passage.