As the political winds shift in the perfect storm of the 2020 election and impeachment, think about this:

GOP strategist Mike Murphy last week said on MSNBC that a Republican senator had told him that as many as 30 GOP senators would vote to impeach President Trump Donald John TrumpFederal prosecutor speaks out, says Barr 'has brought shame' on Justice Dept. Former Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick MORE if it were a secret ballot.

Let’s give those 30 Republicans the benefit of the doubt. Each of them has a conscience. Maybe they can’t live with giving Trump a free pass on using military aid money to press another country to find dirt on his Democratic rival, Joe Biden Joe BidenFormer Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick Bloomberg rolls out M ad buy to boost Biden in Florida MORE.

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At the risk of sounding cynical, it does occur to me that Senate Republicans for the first time see Trump’s scandal possibly costing them their majority.

Next year, 23 Senate Republicans will be up for reelection with Trump at the top of the ticket.

Murphy warned that, given Trump’s antics, Senate Republicans are thinking they are “going to lose Colorado with Cory Gardner Cory Scott GardnerBreaking the Chinese space addiction Trump dumbfounds GOP with latest unforced error Billionaire who donated to Trump in 2016 donates to Biden MORE. We’re going to lose Maine with Susan Collins Susan Margaret CollinsDemocratic senator to party: 'A little message discipline wouldn't kill us' Poll: 57 percent of Americans think next president, Senate should fill Ginsburg vacancy On The Trail: Making sense of this week's polling tsunami MORE. We’re going to lose Arizona with Martha McSally. And the Democrats will put the Senate very much in play.”

At one time, Trump kept Capitol Hill Republicans in line by threatening to have his supporters back a primary challenge to any dissenting GOP member seeking reelection.

Now, that threat has to be weighed against the increasing fear of a weakened president handing the Senate to Democrats.

There is evidence that Senate Majority Leader Mitch McConnell Addison (Mitch) Mitchell McConnellDemocratic senator to party: 'A little message discipline wouldn't kill us' House to vote on resolution affirming peaceful transition of power Republican lawyers brush off Trump's election comments MORE (R-Ky.) sees impeachment imperiling his majority next year.

Last week, McConnell showed independence from Trump by coming out publicly in support of continuing military aid to Ukraine.

More important, he also pushed the White House to share the whistleblower complaint with Congress.

And McConnell has to deal with a well-known Senate Republican daring to separate himself from Trump on the Ukraine scandal — Sen. Mitt Romney Willard (Mitt) Mitt RomneyCrenshaw looms large as Democrats look to flip Texas House seat The Hill's Morning Report - Sponsored by Facebook - Republicans lawmakers rebuke Trump on election Trump dumbfounds GOP with latest unforced error MORE (R-Utah).

Romney said he is “deeply troubled” to see reports of Trump pressuring the Ukrainian president to damage Biden. And he later told reporters: “I can’t imagine being in the Senate or in any other position of responsibility and looking around to see who’s with you. You stand for what you believe in.”

Loss of the majority might prompt Republican senators to start their own version of the wave of retirements — 15 so far — that have hit House Republicans since Democrats claimed that majority in the 2018 midterms.

Team Trump knows it has a problem. The president last week tweeted out a video of Romney’s sad, losing face on the night of the 2012 presidential election.

And Donald Trump Jr. Don John Trump'Tiger King' star Joe Exotic requests pardon from Trump: 'Be my hero please' Zaid Jilani discusses Trump's move to cancel racial sensitivity training at federal agencies Trump International Hotel in Vancouver closes permanently MORE described Romney as “forever bitter that my father succeeded where he so embarrassingly failed.” The son added that Romney is straying from the president because he is “desperate to be loved by the left and the media.”

But Romney is not the only Republican willing to speak out.

Sen. Ben Sasse Benjamin (Ben) Eric SasseWhy a backdoor to encrypted data is detrimental to cybersecurity and data integrity McEnany says Trump will accept result of 'free and fair election' McConnell pushes back on Trump: 'There will be an orderly transition' MORE (R-Neb.) — who was recently endorsed for reelection by Trump — is on the record as saying Republicans “ought not just circle the wagons.”

And outside the Senate, Republican voices challenging Trump for the GOP nomination suddenly, thanks to impeachment, have a larger platform.

Former Massachusetts Gov. William Weld William (Bill) WeldRalph Gants, chief justice of Massachusetts supreme court, dies at 65 The Hill's Campaign Report: Biden visits Kenosha | Trump's double-voting suggestion draws fire | Facebook clamps down on election ads Biden picks up endorsements from nearly 100 Republicans MORE, one of three Republicans challenging Trump for the GOP nomination, said Trump’s telephone call with the Ukrainian president amounted to “treason, pure and simple.”

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The shifting political dynamic among Republicans is a budding version of the sudden shift among moderate Democrats in the House that led Speaker Nancy Pelosi Nancy PelosiDemocratic senator to party: 'A little message discipline wouldn't kill us' Overnight Health Care: New wave of COVID-19 cases builds in US | Florida to lift all coronavirus restrictions on restaurants, bars | Trump stirs questions with 0 drug coupon plan Overnight Defense: Appeals court revives House lawsuit against military funding for border wall | Dems push for limits on transferring military gear to police | Lawmakers ask for IG probe into Pentagon's use of COVID-19 funds MORE (D-Calif.) to announce the start of impeachment.

Pelosi shifted only after seven moderate freshman Democrats — several from districts Trump won in 2016 and all with national security backgrounds — penned an op-ed for The Washington Post calling for impeachment.

Until those moderates stood up, Pelosi had a clear reason to resist calls for impeachment. She was protecting them, and in doing so, boosting her own chances of keeping her House majority.

“As members of Congress, we have prioritized delivering for our constituents — remaining steadfast in our focus on health care, infrastructure, economic policy and our communities’ priorities,” the seven freshmen wrote. “Yet everything we do harks back to our oaths to defend the country. These new allegations are a threat to all we have sworn to protect.”

Now more than half the members of the US House of Representatives — 223 as of Saturday — have come out in support of an impeachment inquiry.

These politicians know how to read polls. And the polls are shifting in favor of impeachment, too.

Before Pelosi’s announcement a majority of Americans opposed impeachment.

Last week, an NPR/PBS/Marist poll found 49 percent backing for an impeachment inquiry and 46 percent opposition.

The preservation of political power, pure self-interest — from both Democrats and Republicans — is at the heart of the start of impeachment proceedings against the 45th president of the United States.

CORRECTION: Under the National Emergencies Act of 1976, members of Congress can force a vote every six months on Trump's declaration of a national emergency. The vote cannot be prevented by GOP leadership. An earlier version of this story included incorrect information.

Juan Williams is an author, and a political analyst for Fox News Channel.