Donald Trump has set out his foreign policy plans while rival Ted Cruz has recruited a presidential running mate.

Republican front-runner Mr Trump said he would put American interests first and vowed to send US troops into combat only as a last resort.

He told an audience of foreign policy experts in Washington: "Our goal is peace and prosperity, not war and destruction."

The billionaire businessman also turned his attention to the Democrats' likely presidential nomination Hillary Clinton during the address.

He criticised Mrs Clinton's handling the 2012 attack on Americans in Benghazi, Libya, and said the US had a "reckless, rudderless and aimless foreign policy" during her time as secretary of state.

Mr Trump's speech was dismissed by former US secretary of state Madeline Albright.

"I've never seen such a combo of simplistic slogans and contradictions and misstatements in one speech," she said.

Mrs Clinton emerged from this week's primaries with a stronger claim on her party's nomination. With four victories on Tuesday, she now has 91% of the delegates needed to clinch the Democratic nomination.

Her opponent, Vermont senator Bernie Sanders, has conceded that the delegate maths is not in his favour. He said his campaign still aims to win the nomination but will also seek to assemble as many delegates as possible to influence the party's platform and message.

He said: "Our job, whether we win or whether we do not win, is to transform not only our country but the Democratic Party, to open the doors of the Democratic Party to working people and young people and senior citizens in a way that does not exist today."

Mr Cruz, meanwhile, has recruited former Hewlett-Packard chief executive Carly Fiorina as his vice presidential running mate.

He announced Ms Fiorina as his vice presidential pick during a rally in Indiana, a state he must win next week in order to keep his White House hopes alive.

He told supporters: "You deserve to know exactly where a candidate stands."

Ms Fiorina painted Mr Trump and Mrs Clinton as a pair of liberals who would do little to shake up Washington.

"They're not going to challenge the system - they are the system," she said.

Ms Fiorina was frequently praised for her tough criticism of Mrs Clinton during her own failed presidential campaign and irritated Mr Trump during Republican debates.

Since dropping out, she has become Mr Cruz's most active supporter, making frequent campaign appearances alongside him and on her own.

Candidates typically wait until they have secured their party's nomination before picking a running mate. But Mr Cruz hopes the addition of Ms Fiorina will attract more voters in Indiana and other remaining states - including her home state of California.

Speaking at a rally in Indianapolis on Wednesday night, Mr Trump criticised the moving, saying: "Cruz can't win, what's he doing picking vice presidents?

"He is the first presidential candidate in the history of this country who's mathematically eliminated from becoming president who chose a vice presidential candidate.

"To me it looks ridiculous, he's not going to get the nomination."

Mr Trump won more than 50% of the Republican votes in Pennsylvania, Connecticut and Maryland, and over 60% in Delaware and Rhode Island.

Mrs Clinton won convincingly in four of the five contests, scoring 56% in Pennsylvania and 63% in Maryland - the two biggest contests of the night. Mr Sanders won the Rhode Island primary with 55% of the vote.

Mr Cruz and Ohio governor John Kasich are trying to stop Mr Trump from securing the 1,237 delegates he needs to secure the nomination and push the Republican race towards a contested convention.

But Mr Trump strengthened his standing this week with a sweep of five north-east primaries, giving him 80% of the delegates he needs.

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