DETROIT (Michigan) • Results from the latest four US states to hold presidential primaries will be critical for both Republican and Democratic parties in their race towards November's election.
Michigan in the industrial Midwest was yesterday the latest test of Republican Donald Trump's appeal to disaffected voters and whether efforts within the party to stop him are working. Republicans also voted in primaries in Mississippi and Idaho and caucuses in Hawaii.
Democratic front-runner Hillary Clinton, meanwhile, was hoping to expand her delegate lead in primaries in Mississippi and Michigan, where rival Bernie Sanders is trying to slow her march.
But while Mrs Clinton and Mr Sanders maintained a polite show of non-aggression, the Republican camp geared up for a battle over which candidate wins the party establishment's support.
At a town hall meeting hosted by Fox News in Detroit on Monday, the rivals carefully passed over questions designed to pit them against each other.
Asked whether he is more trustworthy than Mrs Clinton, Mr Sanders said: "I will let the people of the United States make that decision."
Mrs Clinton, asked whether she views Mr Sanders as an opponent or an ally, called the Vermont senator an ally.
Asked if he would be willing to become Mrs Clinton's running mate, Mr Sanders said he is "running this campaign to win". Mrs Clinton said she was focused on the primary, not who her running mate might be.
Mrs Clinton is already halfway to getting enough delegates to secure the nomination. Mr Sanders needs a major score in the latest round of delegate-rich primaries under way yesterday as well as next week in Florida, Illinois, Missouri, North Carolina and Ohio. Michigan alone has 130 Democratic delegates up for grabs.
Mrs Clinton is leading Mr Sanders by almost 200 pledged delegates won in earlier primaries and caucuses. With super delegates - party members who are free to choose who to support - Mrs Clinton has 1,130 of the 2,383 needed to win the nomination, compared with 499 for Mr Sanders, according to an Associated Press tally.
Meanwhile, Mr Trump went into yesterday's Michigan Republican primary holding a double-digit lead in the opinion polls.
An NBC News and Wall Street Journal poll on Sunday showed Mr Trump at 41 per cent, followed by Mr Ted Cruz at 22 per cent, Mr Marco Rubio 17 per cent and Mr John Kasich 13 per cent.
However, a Monmouth University poll released on Monday showed 36 per cent of likely Republican primary voters support Mr Trump in Michigan, with Senator Ted Cruz at 23 per cent and Governor John Kasich in third place with 21 per cent. Senator Marco Rubio had 13 per cent support.
With Mr Trump ahead and Mr Cruz consolidating his second-place status, the party establishment faces having to embrace what some consider the lesser of two evils.
That could mean backing Mr Cruz - the ultra-conservative Texas senator once reviled by fellow Republicans as a "wacko bird" - at the expense of Mr Rubio, the establishment choice, who is lagging behind and facing calls to give up.
However, Mr Rubio has had a much-needed boost, if not an outright endorsement, from previous presidential candidate Mitt Romney, who recorded get-out-the-vote calls for Mr Rubio's campaign that were sent to voters in the four states that voted yesterday.
Mr Romney indicates that he is calling on behalf of Mr Rubio but only urges voters to cast ballots for "a candidate who can defeat Hillary Clinton and who can make us proud".
He has resisted offering an endorsement of his own, having also praised Mr Cruz and Mr Kasich in remarks last week.
BLOOMBERG, NEW YORK TIMES