Errol Louis is the host of "Inside City Hall," a nightly political show on NY1, a New York all-news channel. The opinions expressed in this commentary are his own.

(CNN) President Trump's effort to strong-arm Senate Republicans into repealing Obamacare has not been subtle. But it's not likely to succeed.

"Any senator who votes against starting debate is really telling America that you're fine with Obamacare," Trump told a group of assembled senators Wednesday, having invited the entire GOP conference to the White House for lunch and a strategy discussion.

In case the point was lost on anybody, Trump gestured to Sen. Dean Heller of Nevada -- seated next to the President -- and said: "Look, he wants to remain a senator, doesn't he? ... I think the people of your state, which I know very well, I think they're going to appreciate what you hopefully will do."

Ouch.

Heller is widely considered the senator most likely to be voted out of a job next year: a recent poll showed him losing, 39% to 46%, against an unspecified opponent. Democrats have accordingly recruited Nevada Rep. Jacky Rosen to oppose him, and have named Heller their top target in 2018.

Heller later downplayed the White House squeeze play, calling it, "just President Trump being President Trump." But he didn't give any sign of changing to a "yes" vote on the repeal of Obamacare.

The hard reality facing the White House is that a critical mass of senators who are needed to pass a real bill have sized up the politics in their respective states. And in several cases, key senators have concluded their voters don't want to see Obamacare dismantled.

In Nevada, Heller has seen the state's popular Republican governor, Brian Sandoval, argue strongly against rolling back the expansion of Medicaid coverage, a key part of Obamacare that benefits many low-income and elderly patients.

Sen. Susan Collins of Maine is another lawmaker whose "no" vote is unlikely to be changed by Trump. "Repealing without a replacement would create great uncertainty for individuals who rely on the [Affordable Care Act] and cause further turmoil in the insurance markets," she said

Small wonder that Collins ranks as the sixth most popular senator in America. Those who favor repeal seldom take into account the fact that what most concerns many voters is sheer uncertainty , the fear of making a wrong choice that harms their families.

Sen. Shelley Moore Capito of West Virginia is another popular senator, having won her seat in 2014 by one of the largest margins in state history. Her state is battling a drug addiction problem so severe that a program that covers the cost of funerals for the indigent cannot keep up with the death toll

The Medicaid expansion covers more than 40% of West Virginia's addiction and mental health costs, something Capito said she won't vote to cut. "I did not come to Washington to hurt people," she said, memorably

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All the presidential bluster in the world won't change political and health conditions on the ground in states like Nevada, Maine and West Virginia. Until poor people don't need help to get health insurance, Trump is unlikely to get the full repeal of Obamacare he promised on the campaign trail.

As the old saying goes: All politics is local. That's a pre-existing condition Trump can't change.