Iowa

It's all beginning to resemble a bad flashback for the second-time Democratic presidential candidate, who once again finds herself barnstorming through the frozen stretches of Iowa with a diminished lead in the polls and an underdog rival on the rise.

CTE, which can be diagnosed only after death, has been found in the brains of dozens of former football players.

President Barack Obama hasn't endorsed a Democratic successor, but he's now revealed some personal pros and cons in the fight between Hillary Clinton and Bernie Sanders.

He's told supporters "We are not just picking a political party, we are picking the very identity of our nation."

Shouting over each other at times, the two engaged in some of their toughest exchanges of the campaign, underscoring the narrowing race in Iowa and New Hampshire.

After months of predicting a comeback for their preferred candidates, Republican establishment leaders now concede the first two contests of the presidential race, in Iowa and New Hampshire early next month, are Donald Trump's and Ted Cruz's to lose.

The expectations game for "establishment" candidates has added intrigue to the final sprint to Iowa's lead-off caucuses. While the fight for first place has settled into a two-way race between conservative favorites Ted Cruz and Donald Trump, some of the biggest unknowns surround the candidates for whom a loss in Iowa could still be viewed as a win.

Wary of another mishap in Iowa, Clinton is preaching a message of urgency, challenging her supporters to dig in during the final month before the state's lead-off presidential caucus.

The horse race is far from over, especially on the Republican side, so here are a few key dates to keep in mind.

He's telling them they can trust him because his poll numbers are horrible in New Jersey based mostly on how voters feel about Christie spending a lot of time away from the Garden State.