Thom Tillis wins North Carolina Republican primary election

In his victory speech, Tillis pledged to "change the mess of Obamacare"

A North Carolina Senate candidate backed by the Republican Party establishment has won the party's nomination to face Democratic Senator Kay Hagan in the November election.

State House Speaker Thom Tillis defeated Mark Harris and Greg Brannon, who were seen as insurgent candidates.

Mr Tillis avoided a runoff election by earning 46% of the vote in the eight-person race on Tuesday.

Republicans aim to wrestle Senate control from the Democrats in November.

"I want to go to Washington and clean up Kay Hagan's mess," Mr Tillis told supporters.

"If we want to change the mess of Obamacare, we have to change our senator," he said, referring to President Barack Obama's signature healthcare reform law, which Republicans uniformly despise.

'Rigged the system'

Republicans have sought to capitalise on Democratic US President Barack Obama's low approval ratings and dissatisfaction with the healthcare law in their effort to wrestle six seats from Democrats and take control of the US Senate in November.

"Thom Tillis has spent his time in Raleigh pushing a special-interest agenda that has rigged the system against middle-class families," Ms Hagan wrote in a statement. "This is not an agenda that works for working families, and his priorities are out of sync with our common-sense North Carolina values."

Ms Hagan was elected in the 2008 Democratic wave and is seen as vulnerable in her first bid for re-election.

Elsewhere on Tuesday, Republican House Speaker John Boehner easily defeated two candidates associated with the right-wing populist tea party movement in the Ohio Republican primary election.

Republican Congresswoman Susan Brooks also beat challengers, winning 75% of primary votes in Indiana.

The North Carolina primary in particular was viewed as a test of the Republican establishment's ability to exert its influence on the nomination process and keep more divisive tea party candidates off the ballot in November.

In the 2010 and 2012 election cycles, the Republican Party watched as popular tea party candidates won party primaries only to flame out in the general election because their strident rhetoric turned off independent voters.