The MSNBC host said a rosy scenario for Dems would be to lose five seats, not six.
The former Massachusetts GOP senator has taken a hit from recent Democratic attacks.
The GOP senator's approval drops 12 points in the last year in a Democratic automated poll.
The Family Research Council endorsed Ben Sasse in the competitive Nebraska GOP Senate primary.
The former president will campaign in Kentucky for Mitch McConnell's Democratic opponent.
The Iowa Democratic Senate hopeful became the first candidate to visit to all 99 counties in the state.
The Republican is challenging Senate GOP leader Mitch McConnell.
BIPAC is backing a number of Republicans facing Tea Party primary challengers in its first endorsements.
The conservative group points to the Mississippi senator's votes to raise the debt limit.
The GOP Senate hopeful talks about his religious values and vision for the country.