McCarthy, who was endorsed by Speaker Paul Ryan Paul Davis RyanKenosha will be a good bellwether in 2020 At indoor rally, Pence says election runs through Wisconsin Juan Williams: Breaking down the debates MORE (R-Wis.) to lead the GOP caucus after his retirement, sent out a “Dear Colleague” letter touting his efforts to mitigate the midterm losses, asserting he had in the past "helped build a majority from a deeper hole" and will do so again.

The California Republican said he will be "a listener every bit as much as a leader" and would do everything within his means to protect the current Congress’s accomplishments from being unwound under a "Pelosi-led House,” a reference to current Minority Leader Nancy Pelosi Nancy PelosiPelosi: Trump hurrying to fill SCOTUS seat so he can repeal ObamaCare House lawmakers reach deal to avert shutdown Centrist Democrats 'strongly considering' discharge petition on GOP PPP bill MORE (D-Calif.).

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"I expect to use every tool at our disposal to deliberately challenge House Democrats and move the Senate to the right," he wrote. "A surefire way to motivate me to is to argue: 'that’s never been done before.' I believe we must embrace unconventional methods and strategies if we are to maximize our leverage and put wins on the board."

McCarthy said he will "draw a contrast with the radical left," adding while Democrats may have taken back the power in the House, he believes the GOP can gain momentum with voters ahead of 2020.

"We may have lost this battle, but the struggle for America’s future is just beginning. And the terrain now shifts in our favor, with at least a dozen seats in Trump-carried districts providing opportunities for us to go on offense starting today," he wrote.

"More importantly, we have seen where Democrats want to take our country— open borders, government-run healthcare, impeaching President Trump Donald John TrumpOmar fires back at Trump over rally remarks: 'This is my country' Pelosi: Trump hurrying to fill SCOTUS seat so he can repeal ObamaCare Trump mocks Biden appearance, mask use ahead of first debate MORE, and crushing debt for our kids and grandkids. We simply cannot let that happen."

Rep. Jim Jordan James (Jim) Daniel JordanSunday shows preview: Justice Ginsburg dies, sparking partisan battle over vacancy before election House passes resolution condemning anti-Asian discrimination relating to coronavirus Republicans call for Judiciary hearing into unrest in cities run by Democrats MORE (Ohio), a leading voice in the conservative House Freedom Caucus, is also vying for the top GOP position in the lower chamber.

Jordan argues the party needs new leadership overhaul if they are going to win back the House in 2020.

"Now that we're in the minority, that's about all we can do is debate, but fight hard in the debate for the principles, for the things that we know the American people sent us here to do in 2016. Show them that we deserve to be back in power in 2020," Jordan, who in July announced he was challenging McCarthy to be the next Speaker, told Hill.TV on Wednesday.

Both Jordan and McCarthy are close allies of President Trump.

—Updated at 2:26 p.m.