US Democrats were celebrating their revived prospects for the November mid-term elections yesterday.

A string of primary results put paid to the notion of an anti-establishment mood sweeping the country.

In the biggest race, in Colorado, President Barack Obama’s favoured candidate secured the Democratic Senate nomination, while the Republicans picked a maverick conservative with links to the Tea Party movement and questionable appeal to the mainstream electorate.

The result, mirrored by Republican races in three other states that nominated outsiders, suggests the supposed anti-establishment fervour is a Republican phenomenon that may hurt the party’s chances at the polls.

The Republicans are banking on an anti-Washington mood to help them overturn the Democratic majorities in the House of Representatives and the Senate.

Ken Buck, who won the Republican nomination in Colorado, was favoured by many in the conservative Tea Party movement, but he was shunned by most supporters of the mainstream Republican Party.

Mr Buck is the fourth Tea Party candidate to win a Republican Senate nomination this year over the party leadership’s pick.

Mr Buck will go up against Democrat Michael Bennet, the incumbent Colorado senator, who retained the nomination despite a challenge by his rival Andrew Romanoff.

The White House backed Senator Bennet’s campaign, which paid off with a comfortable nine-point lead and a much-needed fillip for Mr Obama, whose support was seen as a double-edged sword for some candidates.

While the Republican nomination races reflect the growing strength of the party’s right wing, they highlight a potentially self-destructive trend in which activists repeatedly pick candidates on their anti-establishment credentials over those approved by the party as more electable.

Rand Paul, the conservative darling who won Kentucky’s Republican Senate nomination this year, was quickly shuffled out of the media glare by party officials after a series of gaffes, including his public questioning of the wisdom of the Civil Rights Act.

And Mr Buck was caught on tape last week saying he deserved the party nomination over his female rival because he did not “wear high heels”.

Republican voters showed a similar blindness to reality in their choice of candidate to run for Colorado governor.

A recent suggestion by Dan Maes that a bicycle-sharing scheme may “threaten our personal freedoms” and lead to greater UN influence in the US has only heightened the Republican fears about the gubernatorial race.

In Connecticut, the Republicans nominated another colourful but decidedly untested candidate to compete for the Senate seat being vacated by Democratic incumbent. Linda McMahon is former chief executive of World Wrestling Entertainment, which stages rigged fights featuring scantily clad women, wrestlers and dwarves bashing each other, sometimes with chairs.

She won easily after pouring millions of dollars of her money into the race, and has pledged to spend another $US50 million ($55.6m) on her Senate campaign. The Democrats say they will not hesitate to use her past against her in November’s poll.

“Connecticut Republicans today nominated a corporate CEO of WWE, under whose watch violence was peddled to kids, steroid abuse was rampant, yet she made millions,” said Robert Menendez, head of the Democratic Senatorial Campaign Committee. “McMahon has built an empire peddling violent, sexually explicit material that glorifies the exploitation of women and the mentally disabled.”