ANNAPOLIS, Md. (AP) — Under pressure to help unify his party, Republican presidential hopeful Newt Gingrich pledged Tuesday to support Mitt Romney if the former Massachusetts governor wins enough convention delegates to clinch the nomination by the end of the GOP primary season in June. If Romney falls short, "I think you'll then have one of the most interesting, open conventions in American history," the former House speaker said as he campaigned for votes in next week's Maryland primary.