Former congressman Joe Walsh probably won't win his primary challenge to President Donald Trump, but Walsh's media savvy and heavy-hitting criticisms could batter Trump going into the general election.

Walsh is highly unlikely to actually defeat Trump, who has close to 90% approval among Republican voters and already has the backing of the Republican National Committee.

In recent history, former Presidents Gerald Ford in 1976, Jimmy Carter in 1980, and George HW Bush in 1992 all lost their general re-election bids after facing tough primary challenges.

Thomas Schwartz, a professor of political science and history at Vanderbilt University, told Insider that Walsh is far more ideologically similar to Trump than those presidents' primary challengers.

"Where Walsh could be interesting is the fact that he is media-savvy and he might be able to provoke Trump ... and get a reaction from him," Schwartz said.

On Tuesday, September 24, Business Insider Today will host two of the Republican presidential candidates challenging President Donald Trump in the 2020 GOP presidential primary.

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On Tuesday, September 24, Business Insider Today will host two of the Republican presidential candidates challenging President Donald Trump in the 2020 GOP presidential primary: former GOP congressman Joe Walsh, and former Governor Bill Weld of Massachusetts.

Neither Weld or Walsh are likely to succeed in their primary challenges to Trump, but Walsh's media savvy and heavy-hitting criticisms could batter Trump going into the general election.

Walsh served one term in the House of Representatives representing Illinois from 2011 to 2013 before losing his re-election bid and becoming a conservative radio show host. Later, he became one of Trump's most prominent critics on the right.

While Weld and former Gov. and Rep. Mark Sanford of South Carolina are challenging Trump in the GOP primary from the center, their comparatively subdued presences on the trail have failed to make much of a splash among Republican primary voters.

Unlike Weld, Walsh is a staunch ideological conservative. But Walsh is betting on Republican fatigue with Trump's impulsive and dysfunctional governing style, the way he personally demonizes his opponents, and his frequent lies.

Read more: How to watch the first-ever 2020 Republican presidential debate

"I really do believe that privately, the vast majority of Republicans are sick and tired of Trump. They don't like him. They're tired of his lies. They're tired of his insults. They're tired of all of it. They just don't say that publicly," Walsh said in an August interview with Insider.

Walsh is highly unlikely to actually defeat Trump, who has 88% approval within the Republican party, according to Gallup, and already has the backing of the Republican National Committee.

Even though Trump and Walsh are more ideologically similar than previous candidates and the presidents they primaried, Walsh's hard-hitting, in-your-face style and near-constant onslaught of criticisms against Trump could damage the president going into the general election contest.

Business Insider Today's GOP primary debate will run from 7 PM to 8:30 PM EST on September 24, and will be exclusively live-streamed on Business Insider Today's Facebook Watch page.

Previous presidents have suffered from serious primary challenges

"I find it hard to see him as a serious challenge, electorally at least," Vanderbilt University political science and history Professor Tom Schwartz said of Walsh in a Tuesday phone interview with Insider.

"There's not a lot of room to run to Trump's right in a way that Walsh is trying to do," Schwartz said. "Where Walsh could be interesting is the fact that he is media-savvy and he might be able to provoke Trump ... and get a reaction from him."

In recent history, three previous presidents have lost their general re-election bids after facing serious primary challenges.

In the aftermath of the Watergate scandal in 1976, Ronald Reagan primaried President Gerald Ford, who eventually lost the general election to Jimmy Carter.

Read more: Joe Walsh wants to beat Trump and save the Republican party. But he still defends calling Haiti a 's---hole country.'

But Carter himself was weakened in 1980 both by an economic downturn in America and a primary challenge from the left posed by Sen. Ted Kennedy of Massachusetts, who trounced Carter in 12 states. While Carter made it through the primary, Reagan went on to defeat him in the general.

And in 1992, George H.W. Bush was challenged from the right by Patrick Buchanan, who promoted a more obviously right-wing, populist, nationalist agenda as a contrast to Bush's more centrist policy positions and embrace of globalism. Like Carter, Bush was faced with a recession at the end of this first term, and lost in the general.

"George H.W. Bush had moved significantly and had been moderate, especially in his agreement to raise taxes with the Democrats in 1990 that he really gave Buchanan an opening," Schwartz said, arguing that Buchanan's vocal presence at the RNC may have hurt Bush. "I don't see that Trump has given Walsh the same opening."

In 1992, George HW Bush was primaried from the right by Patrick Buchanan. Diana Walker//Time Life Pictures/Getty Images

Walsh is far more similar to Trump on policy than previous presidents and their challengers

Walsh told Insider that on policy, he espouses the Tea Party-aligned positions of supporting limited government spending and limited immigration, specifically taking issue with Trump's imposition of tariffs, the soaring national debt, and his failure to build a wall on the Southern border.

While Walsh has gone all in to criticize Trump's behavior and conduct in office, he told Insider he agrees with several of Trump's other policy positions, including his focus on nominating conservative judges, de-regulating private industry, aligning with the National Rifle Association of gun issues, and the administration's decision to move the US embassy in Israel to Jerusalem.

Schwartz said in previous primary challenges, stark differences in ideology helped primary challengers facing long odds truly distinguish themselves and stake out sharp contrasts in order to draw divisions within their own party and weaken their opponents.

"Pat Buchanan was genuinely a much more conservative figure and attacked Bush on that basis. Ted Kennedy was much more liberal than Jimmy Carter and represented a culturally and regionally different part of the Democratic Party," he argued.

Read more: Republican primary voters are annoyed that their party is canceling primaries to benefit Trump

As Schwartz noted, it's hard to specifically determine how much of Ford, Carter, and Bush's general election losses can be attributed to the beatings they took in the primary.

But if Walsh's media-centric strategy actually makes an impression and gets under Trump's skin, inter-party attacks and feuding between the two camps could lead to more voter fatigue and ultimately depress turnout.

"When you're being attacked, it can discourage your own voters from voting or convince them to vote for someone else," Schwartz said, arguing that Buchanan's insurgent primary challenge helped "pave the way" for billionaire Ross Perot's third-party run for president, in which he ended up significantly splitting the vote and contributing to Bush's general election loss in 1992.

He predicted that at best, Walsh's campaign could be "an annoyance to the extent that he might require Trump to spend any money or divert any attention to him."

But If Trump doesn't take the bait and engage with Walsh, it's unlikely to have a meaningful impact on the race.

Joe Perticone contributed to a previous version of this report.