Cruz's victories in Saturday's caucuses in Kansas and ME have helped solidify his second place standing to Trump in terms of pledged delegates for the Republican nomination.
Trump has hit Rubio for missing Senate votes and lately has called for him to drop out of the race for the GOP nomination. Trump won the Louisiana primary and the Kentucky caucus but by less than five percent in each state.
"Florida has become an absolute do-or-die state for Marco Rubio", said Baker, who has endorsed the senator.
How many delegates up for grabs?
In fact, he claimed Sunday on CBS's "Face the Nation" that some journalists - apparently convinced that Trump will be the GOP nominee - have actually told him privately that they are holding their best Trump stories for the general election, so they will be more effective.
On the Democratic side, the Monmouth poll found former Secretary of State Hillary Clinton beating Vermont Sen.
"At the outset of this campaign, I promised I would support the Republican nominee" , he said.
What states are voting March 8?
Romney added, "I'm not running and I'm not going to be running". Leaders in Washington who assumed hard-liners such as Cruz represented a minority view have been left wondering if they're the ones out of step with voters.
Overall, Clinton had at least 1,121 delegates to Sanders' 479, including superdelegates - members of Congress, governors and party officials who can support the candidate of their choice.
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. Instead of addressing the conference, Trump held a rally in Kansas, a state Texas Sen.
In a statement after he won Nebraska, Sanders hammered this point home, saying it was contests like this one that will help propel his campaign into the summer.
Clinton and Sanders also faced off in a televised debate in Flint, Michigan, just two days before a crucial primary in that delegate-rich northern industrial state.
Cruz dealt his opponent a bloody nose on Sunday (NZT) when he snatched victory in Kansas, a state Trump was expecting to win. It takes 2,383 delegates to win the Democratic nomination. Since Trump losing is a condition precedent to an ultimate triumph by any Establishment-backed candidate, that's where the rooting interests of Team Rubio will lie.
Since delivering his blistering assault on Trump last week, Romney has been ubiquitous on television, making the case against Trump, the Republican front-runner, and even indicating he would vote for a third-party candidate rather than Trump.