Image copyright AP Image caption Mrs Clinton is favourite to become her party's presidential nominee but Mr Kasich is an underdog in his party

The New York Times has endorsed Democrat Hillary Clinton and Republican John Kasich in their bids to become their parties' presidential candidates.

The liberal newspaper's opinion editors said Mrs Clinton was "one of the most broadly and deeply qualified candidates" in modern history.

It called Mr Kasich, an outsider in the Republican race who is trailing in the polls, the "only plausible choice".

The move comes days before Iowa voters become the first to pick a candidate.

The endorsement of Mrs Clinton from one of the top-selling titles in the US is no surprise; the NYT backed the former secretary of state in her losing bid for the presidency against Barack Obama in 2008.

The NYT had praise for Mrs Clinton's main rival, Bernie Sanders, but the paper said he "does not have the breadth of experience or policy ideas that Mrs Clinton offers".

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Assessing the Republican field, Saturday's NYT editorial gave a damning verdict on the two leading contenders.

Frontrunner Donald Trump "has neither experience in nor interest in learning about national security, defence or global trade", the paper said. Ted Cruz "will say anything to win".

Instead, the NYT plumped for Ohio Governor John Kasich as "the only plausible choice for Republicans tired of the extremism and inexperience on display in this race".

Mr Kasich tweeted he was "proud" to gain the NYT's support, even though the paper has been a frequent focus of criticism for US conservatives.