WASHINGTON: Republican presidential front- runner Donald Trump has said that he prefers to run against Democratic leader Hillary Clinton in the elections and not against Vermont Senator Bernie Sanders despite that he is giving a tough time to the former secretary of state.

"Now Bernie's over, I guess. It's over for Bernie. I don't want to run against Bernie," Trump told his supporters in Pennsylvania, where the Republican presidential primary is scheduled to be held on April 26.

"I want to run against crooked Hillary Clinton. We are going to beat her so badly. Is there anyone more crooked than this woman?" Trump said, as he appeared to be confident of bagging the party's presidential nomination despite being quite far away from the necessary 1237 delegates to get this.

However, he praised Sanders for his tough fight against Clinton. "(Sanders) said she suffers from bad judgement and she said - now I don't know, I think she's qualified, I guess. But that doesn't mean she's good," he said.

"He said she's not qualified to be president. Now what he meant is because her judgement is so bad- so Bernie Sanders, not me, said she's not qualified. So now I'm going to say: She's not qualified, OK?" Trump said.

"We have all of the mistakes Hillary made as secretary of state. We have a mess. The war in Iraq has been devastating. We have probably spent USD 4 trillion in the Middle East," the Republican front runner said in his speech.

Meanwhile, the former Republican presidential candidate and Speaker of the House of Representatives Newt Gingrich said that Trump is a presumptive nominee and urged party leaders to unite behind him.

The Republican National Committee (RNC) leadership continued to its meeting in Florida over the various laws related to the convention.

Trump personally did not attend the meeting, but was represented by his close aides. The other two presidential candidates, Ted Cruz and John Kasich, appeared before the RNC.

At his Pennsylvania rally last evening, Trump refused to go by the advice of his aides who asked him to wait so as to let a large crowd waiting outside to come inside the venue.

"So I am supposed to wait a half an hour because there are thousands of people outside trying to get in. I can't do that to you, so we are going to come on right now," he said off-stage.

"I've never done that before. I've never introduced myself. They didn't quite say it right the first time. We have thousands of people outside. They're going to pour in, they're filling up the floor. Let's start a little bit early. To hell with this," said Trump, who has 845 delegates to his kitty.

His nearest primary rival Senator Ted Cruz from Texas has 559 and the Ohio Governor John Kasich 148. The next round of primary elections are scheduled in the states of Maryland, Pennsylvania, Connecticut, Delaware and Rhode Island.

Trump needs to win big in these states to ensure that he gets the necessary 1237 votes to become the party's nominee before the Cleveland convention in July.

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