There are 35 Senate seats up for grabs this November, but in 21 there are no debates scheduled among the main candidates, an ABC News analysis found.

One race's lack of debates has surprised many observers: the Texas contest between James Talarico, a Democratic state representative, and Ken Paxton, a Republican and former state attorney general.

Polls in the typically Republican state suggest that Talarico could be in reach of a surprise win. Should he succeed, he could help give Democrats control of the US Senate by flipping one of the four seats they need to create a majority.

Talarico has accepted four debate invitations from different news networks. Paxton has not accepted any of those invitations.

In July, Paxton's campaign spokesperson told media outlets he would debate Talarico. But since then, the campaign and Paxton have said little on the matter.

Trump, who backed Paxton in the Republican primaries, has urged the candidates to debate.

"One thing about not showing up is you lose the opportunity to make the case for yourself, and instead, what you do is you give your opponent the ability and the opportunity to make your case as negative as possible," Peter Trumbore, a political science professor at Oakland University, told the BBC's US partner CBS News last month.

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