Ted Cruz added another victory on Saturday in Colorado, continuing his pursuit of Donald Trump and sending a sure sign that he is the candidate best prepared for a contested Republican convention.

Rather than a primary or caucus, Colorado held conventions of its own to determine how its delegates would be allotted. Mr Cruz has now swept all 34 of those delegates in a show of organisational strength that left the Trump campaign scratching its collective head.

In an embarrassing gaffe that could point to wider deficiencies, the campaign mistakenly instructed supporters to vote for Mr Cruz's representatives in at least one instance.

Mr Trump attributed his loss in Colorado to a "bad system", claiming on Sunday that voters had been "offered all sort of goodies by Cruz campaign".