Republican insiders believe Newt Gingrich’s presidential campaign is on its last legs and say the former House Speaker could leave the race after Tuesday’s primaries in Alabama and Mississippi.

But they also said the famously unpredictable Gingrich could confound expectations and continue on, despite pleas from some conservatives to step aside and give Rick Santorum a head-to-head matchup with Mitt Romney.

A spokesman for Gingrich acknowledged Wednesday that the former Speaker needs to win both of Tuesday’s primaries in the South — considered Gingrich’s stronghold — to remain a credible candidate.