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Trump is set to visit Maine on Friday -- his fourth trip there since June

His visit underscores his campaign's belief he has no electoral votes to spare

Washington CNN  — 

Donald Trump’s campaign raised eyebrows with its announcement of a Friday rally in Lisbon, Maine – his fourth trip to the state since June.

But there’s a method to the Republican nominee’s supposed madness.

Maine and Nebraska are the only two states in the country that divvy some of their electoral votes up by congressional district. Maine is typically a Democratic-leaning state, and Nebraska favors Republicans. But Maine’s sprawling, rural 2nd Congressional District is by far its most conservative territory, likely winnable for Trump. And Nebraska’s Omaha-based 2nd Congressional District is a target for Hillary Clinton.

So Trump will visit Maine on Friday, and running mate Mike Pence will make a stop in Omaha on Thursday morning.

What these movements reflect: Despite months of trying to turn blue-leaning Rust Belt states like Pennsylvania and Michigan competitive, Trump’s campaign knows it’s in a battle for every single electoral vote – with no margin for error.

Public polls and early voting results show that Trump’s most viable path to the 270 electoral votes he needs to defeat Clinton runs through both of those districts.

Compared to the 2012 electoral map, Trump needs to hold the competitive states of North Carolina, Arizona, Georgia, Utah and Nebraska’s Omaha-based district, but also win Iowa and Ohio – two states where polls have shown him with a narrow lead – as well as Florida, Nevada, New Hampshire and Maine’s second district. That adds up to 270 electoral votes on the nose – the number it takes to win the presidency.

It’s the political equivalent of a triple bank shot. But without sudden movement elsewhere on the map, it’s also Trump’s most achievable option.

The Trump campaign did not respond to a request for comment about its path to 270.

And while Trump has invested time in Pennsylvania, Colorado, Virginia, Michigan and Wisconsin – five states his campaign has long hoped would slip out of Clinton’s grasp – polls in those states have shown Clinton with an edge that doesn’t appear to be slipping.

That means Trump’s campaign is increasingly focused on a path that runs through the Maine and Nebraska districts, with no margin for error.

The two toughest states included in that path for Trump could be New Hampshire and Nevada.

A Monmouth University poll out Wednesday showed Clinton with a 4-point edge in New Hampshire, 46% to Trump’s 42%. The good news for the Republican nominee: That margin is much narrower than the 9-point lead Monmouth showed Clinton holding there in September.

However, an NBC/Wall Street Journal/Marist poll out Wednesday evening pegged Clinton’s lead at 9 points in New Hampshire – 45% to Trump’s 36%, with Libertarian Gary Johnson at 10% and Green Party nominee Jill Stein at 4%. That poll moved in the opposite direction – with Clinton’s lead climbing from the 2 points the same poll had her at in September.

Trump is set to visit New Hampshire on Thursday in hopes of making inroads in the Granite State.

In Nevada, an NBC/Wall Street Journal/Marist poll showed a tied race – with Clinton and Trump each at 43%, and Johnson at 10%.

A surge in early voting in Clark County, which includes Las Vegas, has buoyed Clinton’s hopes there – but polls show the state is in play.

Trump could also struggle in Florida and North Carolina, where Clinton’s campaign hopes increasingly diverse electorates – including high turnout among Latinos in Florida and African-Americans in North Carolina – will tilt those states in her direction. An Upshot/Sienna College poll in North Carolina this week found Clinton ahead by 7 points. A Bloomberg/Selzer poll in Florida, meanwhile, found Trump up by 2 points.

Ohio and Iowa, meanwhile, appear to have shifted in Trump’s favor since 2012, polls there show.

The two were tied at 45% apiece in the latest Suffolk University poll of Ohio. Trump led by 4 points in the latest Des Moines Register/Mediacom Iowa poll.

Arizona is the most surprising state that Democrats have been able to turn competitive in this year’s race. The latest Monmouth poll there showed Trump ahead by 1 point – 46% to Clinton’s 45%.

Pennsylvania is the state Trump tried hardest to turn competitive – but polls there indicate he hasn’t succeeded. A Quinnipiac University survey in mid-October showed Clinton ahead, 47% to 41% – and other recent public polls have had her lead at least that large.