If real estate mogul Donald Trump is the Republican presidential nominee, it seems likely that the Republicans will lose the Senate and perhaps even the House in November.

Jonathan Tobin in Commentary magazine points out that political scientist Larry Sabato's website currently has only 12 Republican Senate seats considered as "safe" out of the 23 Republican seats open in November. The Democrats have had their eye on Sen. Pat Toomey (R-PA) to retake the Senate, but Toomey's seat had been considered "likely or leaning Republican."

Now, it's a "toss-up," and, according to Tobin, it's all because of Trump:

Pennsylvania has gone Democratic in every presidential election for a generation, but it has often been relatively close. Though Trump clearly has the support of the Republican base — a fact substantiated by his huge win on Tuesday even as Toomey backed Ted Cruz — but polls indicate that in a general election he loses the state to Hillary Clinton in a landslide. As he would elsewhere, Trump loses women by a huge majority. Anger about his stands toward minorities also will generate the kind of turnout that only Barack Obama has generated. That means that Democrats are expecting Trump to both suppress GOP turnout from mainstream Republicans who are disgusted with their party’s likely nominee while hoping that he will also motivate their base in a way their candidate couldn’t accomplish on her own.

The fact that the Democratic nominee in Pennsylvania is a woman named Kathleen McGinty makes it all the more easy for the Democrats in Pennsylvania, so now they can link Trump and Toomey to fuel "the perception that the GOP doesn’t care about the sort of suburban female voter."

Toomey's seat being vulnerable should scare any Republican voter, as he was once considered to be a "strong incumbent," and that's now no longer the case.

The GOP House majority is also vulnerable, as according to Politico as many as 30 House seats could be turned Democrat in November:

“The hardest part about it is having to answer every time the nominee says something,” one worried Republican consultant said. “If he says this, ‘Do you agree?’ If he says that, ‘Do you agree?’ That’s the hardest part, not being able to control your race more. I think Trump makes every district tougher and every state tougher for a Republican.”

To combat that, Republican outside groups are planning a bigger-than-expected fundraising push to protect the House. "I think there are lots of major donors who may have been budgeting to play in presidential who are now saying we need to make sure we keep the House and the Senate,” said one top GOP strategist, who requested anonymity to describe private conversations.

Already, a number of House Republicans are being forced to condemn Trump and his rhetoric. As it becomes increasingly likely that Trump is going to be the GOP presidential nominee, the Democrats' chances of re-taking all three branches of government in November appear to be improving.