Julian Castro becomes TENTH Democrat to qualify for September's presidential debate with a week to go for candidates to make the cut

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Julian Castro became the 10th Democratic presidential candidate to qualify for September's primary debate with a little more than a week to go for contenders to hit the necessary benchmarks in order to make the cut.

Castro hit the 2 per cent mark in his fourth poll on Tuesday, which pushed him on to the debate stage in Houston next month - the third debate of the primary season. 

Qualifications got tougher for the Houston showdown - candidates need to hit two markers: 130,000 individual donors in multiple states and at least 2 per cent in four national polls before the August 28 deadline. 

Julian Castro became the 10th Democratic presidential candidate to qualify for September's primary debate

Candidates have until August 28 to qualify for September's debate in Houston - the third Democratic debate; qualifications have gotten tighter since July's gathering in Detroit (above)

Castro crossed the thresh hold with the latest poll from CNN. He hit the donor mark in July.

'Thank you to our growing number of supporters across the country!,' the former Housing and Urban Development Secretary tweeted at the news.  

Already in September's showdown: Joe Biden, Cory Booker, Pete Buttigieg, Kamala Harris, Amy Klobuchar, Beto O'Rourke, Bernie Sanders, Elizabeth Warren and Andrew Yang. 

The debate is scheduled for Sept. 12 and 13. And it'll be held at Texas Southern University, a historically black public university. Details on the format and moderators have yet to be announced. 

In the first two primary debates, 20 candidates graced the debate stage over two nights - 10 on each evening - in Miami and Detroit.

Should more than 10 candidates qualify for Houston's contest, the event - hosted by ABC News - will likely be broken up into two nights again. 

The Democratic National Committee - which organizes the events - has not said how the candidates will be broken down for the Houston gathering. 

But the committee had good news for the candidates who don't make September's debate - they could still make October's gathering. 

The DNC announced earlier this month they are giving the candidates until two weeks before the October debate to qualify - and set the start of the qualification period as June 28, which was the same start time as qualifications for the September debate.

This means that all candidates who make September's stage are automatically in October's debate plus it gives those contenders not making the grade for Houston extra time to make the next showdown. 

It's uncertain how much extra time as no date has been set yet for the October gathering. But it could be up to three or four weeks.

Meanwhile, at least three more Democrats have a good chance at making Houston's stage before next week's cut off point. 

In Tuesday's CNN poll, Tulsi Gabbard received 2 per cent, marking her second poll with that number and putting her half way there. Her campaign said she has already hit the donor thresh hold. 

Businessman Tom Steyer - who has yet to participate in a debate - is one poll away from qualifying and has met the donor mark.

Kirsten Gillibrand has only met the 2 per cent mark in one poll and has not hit the donor thresh hold. 

She told the Washington Post Monday that she was about 20,000 donors short.

Meanwhile, Jay Inslee and Marianne Williamson have hit the donor benchmark. 

Tulsi Gabbard (left) and Kirsten Gillibrand (right) are close to qualifying for September's debate

Businessman Tom Steyer - who has yet to participate in a debate - is one poll away from qualifying and has met the donor mark for Houston's gathering

Inslee told MSNBC on Sunday that he was close to the donor thresh hold. 

'We’re just a few thousand away from getting to 130,000,' he said.

His campaign announced Monday he had crossed it. 

And Williamson announced she hit the mark on Tuesday. 

But neither of them have hit the 2 per cent mark in any of the polls the DNC is looking at for debate qualifications. 

Of the other contenders who participated in the first two debates - Tim Ryan, Michael Bennet, and Steve Bullock - none of them have hit either of the two requirements.