Washington (CNN) Donald Trump 's path to 270 electoral votes remains precarious -- but with some breaks, he can get there.

Trump's campaign has made clear exactly what its targets are. It is spending $25 million on TV ads in the final week of the campaign in Colorado, Florida, Iowa, Maine, Michigan, New Mexico, North Carolina, Ohio, Pennsylvania, Wisconsin, Virginia, Nevada and New Hampshire.

Those ad buys are based on the assumption that Trump doesn't need extra help to keep Arizona, Georgia, Utah, Texas or any other traditionally red state in the Republican column.

Trump starts with four must-wins: Florida, Ohio, North Carolina and Iowa.

Those -- plus making sure he doesn't surrender other typically Republican states, and winning the one electoral vote that can come from Maine's Second Congressional District -- get Trump to 260 electoral votes.

"We believe 100% that we're winning all four of those. And once we do that, then we put ourselves in a position to win one of those other swing states," Trump deputy campaign manager David Bossie said.

The other targets include bigger states -- Pennsylvania, Wisconsin, Virginia and Michigan, any one of which would put Trump over the top -- and smaller states, Nevada, New Hampshire and New Mexico, of which he'd have to win two.

Those make up Hillary Clinton's firewall, and Trump has to crack it somewhere.

"I think all of those, we are closer in some than others, but we're within the margin of error in many. We are fighting for every single vote," Bossie said.

Here's a look at some scenarios in which Trump could get to 270 electoral votes:

The no-margin-for-error map

This one, according to polls, is probably Trump's best bet -- but it's also one in which he has no margin for error.

Trump could carry every state Mitt Romney won in 2012 (including North Carolina) and flip the Barack Obama states of Florida, Ohio, Iowa, Nevada and New Hampshire.

How tight would this path be? So tight that Trump would also have to lock up Nebraska's Omaha-based congressional district and Maine's rural district to get those single electoral votes. This map places him at exactly 270, without a single electoral vote to spare:

If there's a 'silent majority' of working-class whites

This is Trump's dream scenario, because it cracks Clinton's blue wall of Wisconsin, Michigan and Pennsylvania -- which he hasn't been able to win in polls.

In this map, Trump doesn't need to sweat tight races in Nevada or New Hampshire. As long as he locks in Florida and Ohio, he could afford a fumble like North Carolina, as well:

If Clinton bleeds votes to Gary Johnson

Three smaller, fiercely independent states could tip from Clinton's column to Trump's if she loses many of the Republican-leaning voters who just aren't comfortable with Trump -- not to the GOP nominee, but to Libertarian Gary Johnson.

Those states are Nevada, New Hampshire and Colorado -- all places where Johnson has beaten his poll numbers from big swing states -- and they'd be enough for Trump to win:

If African-American turnout drops

There are signs in the early vote numbers from North Carolina, Florida and Georgia that fewer black voters (who typically back Democrats) are turning out compared to previous election cycles -- resulting in whiter electorates.

That would help Trump in those three states -- and could boost him in Michigan, too, where much of the Democratic vote comes from African-Americans in cities like Detroit and Flint:

If Latinos don't vote as expected

All of a sudden, the West could become much more competitive -- with Trump securing Arizona and having a chance at flipping Florida, Nevada, Colorado and New Mexico.

This scenario would also lock up Florida for Trump, and would allow him to forget about New Hampshire:

If the Northeast loves Trump

Forget Maine's Second District -- perhaps Trump can flip the whole state. And he could take New Hampshire with him.

In this scenario, Trump would vastly outperform expectations among suburban, middle-class voters -- and win the election's biggest prize of all: the Philadelphia suburbs:

CORRECTION: A map in an earlier version of this story mislabeled Florida. In the no-margin-for-error map, Florida would go to Clinton.