Republican U.S. presidential candidate Donald Trump gestures during a campaign rally in Tampa, Florida, Thomson Reuters Presumptive Republican presidential nominee Donald Trump blasted Democrats and renewed calls for a ban on Muslim immigration to the US after a gunman on early Sunday morning shot dead 50 people at an Orlando LGBTQ nightclub.

In a statement, Trump called on President Barack Obama to "step down" for not using the words "radical Islamic terrorism" and challenged Clinton to use the phrase when referring to the Orlando attack which ISIS claimed responsibility for.

He also warned against admitting migrants from the Middle East and renewed calls for a ban on Muslims entering the US.

"What has happened in Orlando is just the beginning," Trump wrote on Twitter. "Our leadership is weak and ineffective. I called it and asked for the ban. Must be tough."

He added in his statement:

We admit more than 100,000 lifetime migrants from the Middle East each year. Since 9/11, hundreds of migrants and their children have been implicated in terrorism in the United States.

Hillary Clinton wants to dramatically increase admissions from the Middle East, bringing in many hundreds of thousands during a first term — and we will have no way to screen them, pay for them, or prevent the second generation from radicalizing.

We need to protect all Americans, of all backgrounds and all beliefs, from Radical Islamic Terrorism — which has no place in an open and tolerant society. Radical Islam advocates hate for women, gays, Jews, Christians and all Americans. I am going to be a President for all Americans, and I am going to protect and defend all Americans. We are going to make America safe again and great again for everyone.

Clinton has said that the US should increase the number of Muslim refugees allowed into the US, calling on the US to admit 65,000 refugees from Syria due to the humanitarian crisis there.

When Trump previously called for a ban on Muslims entering the country, critics blasted the proposal as ineffective and bigoted. Since then, Trump backed away from that rhetoric and said that the ban was "just a suggestion."

Paul Manafort, the chief strategist and chairman for Trump's campaign, said last month that Trump would "moderate" and "soften" his stance on a Muslim ban.

A representative for the Clinton campaign did not immediately respond to a request for comment from Business Insider.