From the historically most accurate pollster in this race

Des Moines Register Iowa Poll

Trump 28% (+6)
Cruz 23% (-2)
Rubio 15% (+3)
Carson 10% (-1)
Paul 5% (-)
Christie 3% (-)

— TSE (@TSEofPB) January 30, 2016

It looks like the attacks on Ted Cruz and the doubts about his eligibilty have had an impact on the Senator from Texas.

Whilst the Democratic race is

Whilst the Des Moines Register Iowa Poll for the Dems has

Clinton 45% (+3)
Sanders 42% (+2)
O'Malley 3% (-1)

— TSE (@TSEofPB) January 30, 2016

But winning the GOP nomination is one thing, winning the White House is another

Gallup finds that Trump most unpopular contender since 1992.https://t.co/l7XYGyiXqZ? pic.twitter.com/vAP1vhYi3U

— Mike Smithson (@MSmithsonPB) January 30, 2016

Betfair implied odds on Trump being the next President is less than 20% pic.twitter.com/qlNCJzjzOO

— TSE (@TSEofPB) January 30, 2016

Updated odds for Monday's Iowa caucuses.https://t.co/9MQnMjk3rW pic.twitter.com/dZlaiYXMIh

— Ladbrokes Politics (@LadPolitics) January 31, 2016

TSE