Hillary Clinton's Lead Over Bernie Sanders Narrows Slightly in WSJ/NBC Poll

John Kasich battled Trump in early returns in MI, the biggest prize of the night, while Ted Cruz ran a distant second in Mississippi.

Trump also pointed to the "great talk" he had with House Speaker Paul Ryan as an example of the type of bridge-building the Republican Party should be doing.

The pair won two states each, with Trump taking Kentucky and Louisiana and Cruz adding ME to Kansas to take more delegates overall than the frontrunner. His recent losses to Cruz, the Texas senator, have raised questions about his durability and given fresh hope to other competitors.

The survey was released on the day Democrats vote in primaries in MI and Mississippi.

The economy ranked high on the list of concerns for voters heading to the polls in MI and Mississippi.

African Americans have supported Clinton in large numbers although many are increasingly supporting Sanders and Trump.

"We welcome you and embrace you", Cruz said.

The poll shows Rubio's geographical strength lies in the southern part of Florida (41% to 30% over Trump), while Trump dominates Rubio in Central Florida, 44% to 22%.

Ted Cruz claims he can stop Donald Trump. About 64% of Republicans said they are satisfied with their options, while 83% of Democrats said the same.

Speaking from Idaho Saturday evening, where he's campaigning ahead of the state's primary on Tuesday, Cruz told the crowd, "The scream you hear, the howl that comes from Washington, D.C., is utter terror at what we the people are doing together".

Asked again on Sunday whether he plans to do so after the March 15 set of primaries including Florida and OH - where Rubio and Kasich will be waging last stands in their home states - Romney demurred. The Republicans are fighting for the votes of the Mitten State, too.

"History will be kind to Republicans who denounce Donald Trump".

Mrs. Clinton leads Mr. Sanders by 48 points among women age 50 and older, by 29 points among nonwhite voters and by 26 points among moderates and conservatives.

Will Cruz Trump the Donald's Deep South Streak?

Romney indicates, at the beginning and end of the message, that he is calling on behalf of Rubio but only urges voters to cast ballots for "a candidate who can defeat Hillary Clinton and who can make us proud", according to a copy of the message obtained by The New York Times.

"I may well at that point", he said.

He insists he's not endorsing anyone, and is not entering the race himself - and only wants to boost Trump's rivals in states where they have a chance of beating the Republican front-runner, with the apparent goal of depriving Trump of the delegates needed to clinch the nomination.