Dean Obeidallah, a former attorney, is the host of SiriusXM's radio's daily program "The Dean Obeidallah Show" and a columnist for The Daily Beast. Follow him @deanofcomedy. The opinions expressed in this commentary are his.

(CNN) After former FBI Director James Comey testified before the Senate intelligence committee this past week, we heard various conservative pundits -- and even Donald Trump Jr. -- take to the airwaves to defend President Donald Trump. But who didn't we see defending him? Congressional Republicans.

Sure, there was Paul Ryan saying , "The President's new at this ... he probably wasn't steeped in the long-running protocols." But then the House Speaker added, "I'm not saying it's an acceptable excuse. It's just my observation."

Senator Marco Rubio, R-Florida, who is a member of the Senate intelligence committee, responded similarly, noting that this all "boils down" to one of two scenarios. Either Trump is simply "a nonpolitician, unconventional figure" who ignores past ways of doing things. Or, as Rubio posited , "is this the action of someone putting together a plan to impede an investigation?"

The best defense Trump saw was from his vocal ally Sen. John Cornyn, R-Texas, noting that at least Comey confirmed Trump was not under investigation by the FBI for possible collusion with Russia. But as Sen. Lindsey Graham, R-South Carolina, later remarked, Trump is "not under investigation for collusion yet. Keep investigating." Adding, while raising Bill Clinton's own scandal that led to his impeachment, "You start with Whitewater and you end up with a blue dress."

And on the Sunday morning talk shows, Republican senators refused to defend Trump's attacks on Comey. Sen. Jim Lankford, R-Oklahoma, called Trump's interactions with Comey "very inappropriate," while Sen. Susan Collins said Trump was wrong to talk to Comey about Flynn.

With friends like these, who needs Democrats?! The reality is that we first saw cracks in congressional Republicans defending Trump's questionable actions after he fired Comey as FBI director last month. As FiveThirtyEight.com quantified, only 12 out of 52 Republican senators publicly defended Trump's decision. In fact, 15 GOP senators actually publicly criticized Trump's firing of Comey, while 21 offered ambiguous responses.

So why are Republicans hesitant to come to the President's defense? Many fear that any allegiance to Trump may cost them in the midterms -- and, more importantly, may cost the Republican Party control of the Senate and the House.

Don't take my word for it. Just last week, second-term Republican member of Congress Martha McSally acknowledged this fear. While at a closed door meeting with banking lobbyists that was secretly recorded , she was heard sharing the way constituents have been talking to her about Trump: "I'm, like, responsible for everything he does, and tweets and says." She then added a concern many of her fellow Republicans must be feeling: "Any Republican member of Congress, you are going down with the ship."

Well if the past is prologue, McSally, from Arizona, is 100% correct. Midterm elections are generally viewed as a way for voters to send a message to the president. And with few exceptions, the president's own political party loses seats in the midterms -- the degree to which typically is tied to the president's approval rating.

With that in mind, congressional Republicans have to be concerned with Trump's poor approval ratings. According to the latest Quinnipiac Poll, reported by CNN, only 34% of Americans approve of President Trump's job performance, a slight drop from the last polling in early April.

History has shown that when a president's approval rating is lower than 50% going into the midterm elections, his party has lost, on average, nearly 40 House seats . Keep in mind the Democrats only need to take 24 seats to regain control of that chamber. (Taking the Senate is more challenging -- but far from impossible -- given that of the 33 seats up in 2018, 23 are held by Democrats, with 10 of those in states Trump won.)

Now, there are some Trump supporters pointing out that Bill Clinton's approval rating five months into his presidency was in the neighborhood of Trump's, yet he won re-election. True, in June 1993, Clinton had a 39% approval rating . But Clinton was dealing with a sluggish economy and a 7% unemployment rate . In contrast, Trump has a booming economy -- thanks in great part to President Obama's sound economic policies -- and an unemployment rate of 4.3% , the lowest in 16 years.

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In any event, Clinton went into the 1994 midterm with a 48% approval rating . What happened in the midterm election? A little thing known as the Republican Revolution , in which the GOP netted 52 House seats and eight Senate seats.

Conservative pundits may love Trump. But congressional Republicans love being re-elected even more. If Trump's approval numbers remain where they are, it won't be long until we see congressional Republicans dump Trump. Not only will they stop defending him, but they will actively run away from Trump. And if Trump's numbers continue to plummet, we may even see some of them run against Trump.