Mr Cruz is hoping to stop Mr Trump in his tracks in Indiana

Meanwhile in the Democratic battle, polls show Hillary Clinton and Bernie Sanders locked in a tight race in Indiana.
However, a Sanders win in Indiana would do little to erase Mrs Clinton's commanding lead.
The Clinton campaign has shifted its focus to other states, opting not to actively campaign or spend money in Indiana.
Mr Trump told supporters on Monday that he is eager turn his attention to the general election.
"You know if we win it's over, and then I can focus," he said at a campaign rally in the state.
Mr Cruz cannot get enough delegates to win the nomination outright, but hopes he can still deprive Mr Trump of a majority.
He has thrown considerable resources into the state in recent days.