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Marco Rubio earned some much-needed positive news with the endorsement of his hometown paper, the Miami Herald, writes Guardian politics reporter Sabrina Siddiqui:

As attention quickly shifts to the March 15 Florida primary, now a do-or-die moment for Rubio’s presidential ambitions, the editorial board made its announcement late Wednesday.

“Floridians should not be stampeded into thinking that it’s all over,” the paper wrote:

In the Republican race, in particular, they have an opportunity to change the course of a deeply discouraging — even embarrassing — campaign narrative by boosting the chances of native son Marco Rubio, the best remaining candidate with a mostly positive message and a practical chance to win the nomination.

Smiles: in Shelby Township, Michigan, on Wednesday. Photograph: Jeff Kowalsky/EPA

The board further expressed doubt that frontrunner Donald Trump had a lock on the Republican nomination, despite his back-to-back wins in early states New Hampshire, South Carolina and Nevada and big victories on Super Tuesday. Rubio has thus far won just one of the states, Minnesota, of the 15 that have taken to the polls in the Republican primary.

Rubio is now pinning all of his hopes on Florida and implored voters in Miami earlier this week to “send a message” that would reset the narrative of the race. The senator is currently trailing Trump in his home state by double digits, according to most publicly available polling, although his aides have said their internal numbers show a closer contest.

At the Ronald Reagan Equestrian Center in Miami, Florida, on Tuesday. Photograph: UPI / Barcroft Media

The Miami Herald, the largest newspaper in south Florida, also endorsed Rubio when he ran for the US Senate in 2010 as an underdog.

This time, the editorial board named several points of difference with the senator – including his positions on abortion, gun control, the health care law, and climate change, as well as his opposition to restoring diplomatic ties with Cuba and low Senate attendance record. It nonetheless said Rubio “does not occupy the same extremist terrain” as Texas senator Ted Cruz and was best positioned to unify a fractured Republican Party.

Rubio also secured the backing of New Mexico governor Susana Martinez, who has often been named as a potential vice presidential pick for the eventual Republican nominee.

“The stakes for our great country are too high – and the differences between the candidates too great – for me to remain neutral in this race,” Martinez said in a statement. “I wholeheartedly trust Marco to keep us safe and ensure a better tomorrow.”

New Mexico governor Susana Martinez speaks to reporters outside the Calvary Baptist Church in Las Cruces, New Mexico in August after an explosion their deemed intended to cause harm. Photograph: Andres Leighton/REX Shutterstock

Rubio’s campaign later announced that she will join him on the campaign trail in Kansas and Florida in the coming days.

Florida’s governor, Rick Scott, confirmed on Thursday that he would remain neutral ahead of the state’s primary. That, too, was a source of relief for Rubio, following numerous reports that Scott was moving toward endorsing Trump.