Donald Trump has hit out at Republicans trying to formulate a new defense for him ahead of the impeachment inquiry ramping up this week with televised public hearings.

The president tweeted: "The call to the Ukrainian President was PERFECT. Read the Transcript! There was NOTHING said that was in any way wrong. Republicans, but it's not perfect, but is not impeachable. No, it is much stronger than that. NOTHING WAS DONE WRONG! "

Kentucky senator Rand Paul who has been putting forward an alternative defense to his own.

Mr Trump has had his claim to Volodymyr Zelensky, in which he asked him to investigate his political rivals, was "perfect".

He has been insistent that the call did not contain a "quid pro quo", namely, that he was withholding military aid and a White House visit until the Ukrainians announced an investigation into Democratic presidential hopeful Joe Biden.

The call prompted an anonymous whistleblower, which in turn to an impeachment inquiry.

Mr Trump has said that he was concerned because he was concerned about corruption in Ukraine and because he thought the European Union should not be a member of the Russian-backed separatists.

Appearing on NBC's Meet the Press On Sunday, Mr Paul offered an alternative defense, suggesting the president should stop having quid pro quo.

He said: "Presidents have withheld help before for corruption.

"So the thing is, I think it's a mistake to say, 'Oh, he did not get what he wanted'. Well, if it's corruption and he believes in corruption then he has every right to withhold help.

"So I think it's a big mistake for anybody to argue …" he did not have a quid pro quo, "and I know that's what the administration's arguing. I would not make that argument. I would make the argument that every politician in Washington, other than virtually, is trying to manipulate Ukraine to their purposes. "

Jake Tapper fact-checks false Trump talking point that Europe does not provide aid to Ukraine

Another Republican, Mac Thornberry congressman, told ABC's This week that it was inappropriate for Mr Trump to be a political opponent, it should not be impeached for it because it is the way he acts "all the time".

He said: "There is not much in the way of a phone call that's different in the public.

"So is there a lot of abuse in the world? I do not hear that. "

The audience hearings begin on Wednesday, with William Taylor, the most senior US diplomat in Ukraine, and George Kent, a State Department official, giving evidence to the House Intelligence Committee.

On Friday, the US Ambassador to Ukraine, Marie Yovanovitch, will give evidence.

While Mr Trump has always been asked for a copy of the text, the White House shows the call to "perfect" – repeatedly tweeting the phrase "read the transcript" – Democrats believe it "Favor", namely investigations into his political rivals.

Lindsey Graham, Republican Chairman of the Senate Judiciary Committee, was staying on message in an interview with Fox News, insisting that the whistleblower should be forced to testify.

Mr Trump has repeatedly called for the whistleblower, who enjoys legal protection from being identified, to be unmasked and cross-examined.

Mr Graham said: "It's impossible to bring this case forward to a situation where they have a chance to cross-examine their biases. So if they do not call the whistleblower in the House, this thing is dead on arrival in the Senate. "

The Democrat-controlled House of Representatives is expected to approve articles of impeachment – essentially charges of wrongdoing – against the president. The Senate, which is controlled by Republicans, would then be expected to hold an impeachment trial to decide whether Mr Trump should be removed from office.