WASHINGTON (AFP) - Presumed Democratic frontrunner Hillary Clinton would comfortably defeat Mr Jeb Bush for president if the two members of their famous US political clans went head to head in 2016, poll results showed Monday.

A CNN-ORC poll showed that former Florida governor Mr Bush, the son and brother of two former US presidents, as the Republican Party's clear front-runner for the White House, nearly two weeks after he announced he was "actively" exploring a presidential bid.

With 23 per cent of respondents' votes, Mr Bush outpaced New Jersey Governor Chris Christie (13 per cent), conservative physician Ben Carson (7 per cent), former Arkansas governor Mike Huckabee and Senator Rand Paul (both 6 per cent) as top Republican contender in the race to see who will succeed President Barack Obama two years from now.

Senator Marco Rubio and congressman Paul Ryan were at 5 per cent support, with several others, including conservative Senator Ted Cruz and Wisconsin Governor Scott Walker, in lower single digits.

Mrs Clinton, who has served as secretary of state, US senator and first lady, came out on top in matchups against all Republican rivals.

Mr Bush fared best, garnering 41 per cent of votes against Clinton's 54 per cent.

Mr Christie was less impressive in a face-off with Clinton, losing 39 per cent to 56 per cent.

Mr Ryan, the 2012 vice-presidential nominee, fared slightly better, earning 41 per cent to Clinton's 56 per cent.

On the Democrats' side, Mrs Clinton bigfoots all potential challengers, claiming 66 per cent support.

Her nearest rival, liberal Senator Elizabeth Warren, earned just 9 per cent, while Vice-President Joe Biden received 8 per cent.

Mrs Clinton's advantage is impressive, but a scenario involving Mrs Clinton herself proves poll numbers are not infallible.

In a December 2006 poll about the 2008 presidential race, then-senator Mr Obama hovered at 17 per cent support for the Democratic nomination, compared with Mrs Clinton's 39 per cent.