He ran unsuccessfully for a Louisiana Senate seat in 2014.
The N.H. governor's approval rating dropped after she advocated halting Syrian refugee resettlement.
Rep. John Fleming joins what could be a crowded field.
Portman has been spending early and often in the Ohio Senate race.
Jonathan Swan 12/05/15 02:21 PM EST
Both Democrats and Republicans oppose the measure, but for different reasons.
The Democratic establishment is behind Grayson's rival, Patrick Murphy.
The incumbent GOP senator says his opponent wants to allow in 200,000.
Jonathan Easley 11/23/15 05:31 PM EST
Independent political watchers say John Bel Edwards benefited from a perfect storm.
Reps. John Fleming and Charles Boustany Jr. have already announced they are running.
Ben Kamisar 11/22/15 09:00 AM EST
Maggie Hassan is in a tight race for Senate, trying to unseat Republican Kelly Ayotte.