Former California Governor Arnold Schwarzenegger joined Republican presidential candidate John Kasich on the campaign trail on 6 March in Columbus, Ohio where both men paid tributes to former First Lady Nancy Reagan who passed away earlier in the day.

"She was one of the greatest first ladies. Extraordinary human being and such a wonderful partner to her husband, to President Reagan, who was without any doubt one of the greatest presidents in the history of the United States," Schwarzenegger said.

Kasich said: "I got to tell you she's now, as she used to say, with her Ronnie and with the Lord and it's great. So God bless them and God bless America for what Ronald Reagan and Nancy Reagan did for this country."

Kasich, one of only four Republican candidates remaining from a starting field of 17, is pushing to win the primary in the battleground state of Ohio where he is governor. He has vowed to erase the US budget deficit without shredding the safety net for poor Americans and has built a base of support among moderate Republicans and independent voters, but has yet to win any state.

Voters in Ohio will cast their ballot in the state's primary on 15 March, along with the delegate-rich states of Florida, Illinois, Missouri and North Carolina.