Perry proposes flat tax, budget plan
- Celebrities help S.F. mayor in campaign video
- Perry, Romney spar over releasing tax returns
- Long-shot Roemer banks on N.H. primary
- GOP chair: States to pay for early primaries
- Obama hangs with stars in Hollywood
- Herman Cain's campaign video blows smoke
- Perry not backing off Obama birther issue
- Analysis: Both sides hit Obama on pipeline
- Cain, Gingrich set for Lincoln-Douglas debate