By James Oliphant
The insurgent candidates in the 2016 US presidential race, billionaire Republican Donald Trump and Democratic socialist Bernie Sanders, can get a huge a lift at Tuesday's (local time) New Hampshire primary elections by defeating mainstream rivals.
In an election year when Americans seem angry at traditional politicians, the two men held strong leads over their respective opponents in New Hampshire, the second state to pick party nominees for the November 8 election to replace President Barack Obama.
For the other Republican candidates, it was a fight for second place in the state behind Trump.
After a strong third-place showing in last week's Iowa caucuses, the first state to hold a nominating contest, Marco Rubio needs another top-tier finish in New Hampshire to demonstrate he is the candidate the party's leadership and wealthy donors should rally behind.
A debate performance by Rubio on Saturday night was widely mocked by Republicans and Democrats, as well as legions on social media, but a robust finish in New Hampshire may help defuse the notion that it did lasting damage.
A WMUR-CNN poll on Monday showed Trump leading in New Hampshire with the support of 31 percent of those planning to vote in the Republican primary.
Rubio was second at 17 percent, followed by Ted Cruz and John Kasich at 10 percent, with a margin of error of plus or minus 5.2 percentage points.
Jeb Bush, a former Florida governor, and former tech executive Carly Fiorina trailed in the single digits.
On the Democratic side, Sanders held a strong poll lead over former secretary of state Clinton.
He disputed Clinton's notion that he had an advantage over her simply because he is a US senator in the neighbouring state of Vermont.
Obama, who has not yet endorsed a candidate from among his fellow Democrats, expressed surprise at the leads in polls held by Trump and Sanders.
"Early on, often times, voters want to just vent and vote their passions," he told CBS News in an interview that aired on Tuesday.