Even before the release of audio of lewd and offensive comments about women Donald Trump made in 2005, and before scores of fellow Republicans called on him to step down, Trump's chances of winning the U.S. presidency were looking slim.

They may now be non-existent.

But if Trump somehow weathers this storm, an electoral map that puts him in the White House can be cobbled together if he can swing just a few battleground states in his direction.

The winner of the U.S. election is not necessarily the candidate who receives the most votes across the country. Rather, victory goes to the candidate with a majority in the electoral college.

With the exception of Nebraska and Maine, all states are winner-take-all — meaning the candidate who wins the popular vote in a state is awarded all of that state's electoral college votes.

A winning presidential campaign, then, is a question of putting together enough states to get a candidate more than half of the 538 electoral college votes, or 270. George W. Bush managed the feat in the 2000 election, for example, despite losing the national popular vote to Al Gore.

Below are a few examples of electoral maps that would give Trump the presidency — along with the difficulties he will have in putting them together.

Trump's path of least resistance

Winning electoral college map for Donald Trump awarding him winnable states.

The easiest path to victory for Trump would be to win all of the swing states with the smallest margins between him and Clinton, the Democratic nominee. These include a number of states that have voted Republican in recent elections and in which Trump has led in the polls on several occasions: Ohio, North Carolina, Nevada, Florida and Iowa.

But, combined with the states solidly in Trump's camp, these would not be enough to push Trump over 270. To get over the top, he would need a big state that has leaned more heavily towards the Democrats throughout this campaign, such as Wisconsin, Pennsylvania, Michigan, Virginia, Colorado, Minnesota or New Mexico.

This is not an impossible map for Trump. But it requires an upset in at least one state.

If Trump loses Ohio

Winning electoral college map for Donald Trump if he also loses Ohio.

Winning Ohio is certainly not a given. The state has swung back and forth between Clinton and Trump in the Presidential Poll Tracker for months. It is a linchpin for the Republicans, however. No Republican has ever won the White House without winning Ohio.

Making up for Ohio's 18 electoral college votes requires a few more Democratic-leaning states to swing to Trump instead. But states do not move in isolation. As FiveThirtyEight has calculated, some states are correlated with others. If Trump does not win Ohio, he is unlikely to win Michigan, Wisconsin, Minnesota or Iowa.

That limits his options. In addition to North Carolina, Nevada and Florida, Trump would also need to win Pennsylvania and either Virginia or Colorado.

If Trump loses Florida

Winning electoral college map for Donald Trump if he also loses Florida.

Trump has shown strong poll numbers in Ohio, leading in the state for weeks at a time. Florida, however, is more of a question mark — and one of the tightest races in the country.

If Trump doesn't win Florida — and with its large Hispanic population, that is seen as a safe bet — his map becomes even more difficult. He would then need to win Ohio, North Carolina, Nevada, Wisconsin, Pennsylvania and one of Michigan, Virginia, Colorado or Minnesota.

Pennsylvania may be one of the harder nuts to crack. Trump has led in Pennsylvania polls only rarely and by very slim margins, while Clinton has held double-digit leads in a few recent polls. The state hasn't voted for a Republican presidential candidate since 1988.

A Midwestern strategy

Winning electoral college map for Donald Trump if he wins more states in the Midwest.

Instead of winning some of the traditional swing states, Trump has mused about winning other states — particularly those in the Midwest or the Rust Belt. His anti-trade message and strong support among whites without a college education suggest that is not an unreasonable strategy.

A Midwestern strategy would mean winning Ohio, Wisconsin, Pennsylvania, Michigan and Minnesota. With those states, Trump wouldn't need Nevada, North Carolina or even Florida.

But history would be against him. Michigan hasn't voted Republican since 1988. Wisconsin hasn't gone for the Republicans since 1982. And Minnesota last voted for the GOP in 1972 — when Richard Nixon beat George McGovern by 23 points nationwide.

Two of these states didn't even vote for Trump in the Republican primaries, with Wisconsin opting for Ted Cruz and Minnesota voting for Marco Rubio.

If Trump loses Ohio and Florida

Winning electoral college map for Donald Trump if he also loses Ohio and Florida.

If Trump cannot win in Ohio or Florida, states that have stuck with the Democrats over the last two election cycles, his map gets very difficult, if not impossible. He would then need to win North Carolina, Nevada, Wisconsin, Pennsylvania and Michigan, as well as another state such as Virginia, Colorado, or New Mexico.

These last three states are not unwinnable for a Republican candidate. George W. Bush won all three in 2004. But these are states in which Clinton has some major demographic advantages.

New Mexico has a very large Hispanic electorate — roughly four times the national average — and its white population is proportionately more college-educated than the norm. Colorado, too, has more college-educated whites, a group that has swung to Clinton in this campaign in big numbers.

Virginia has been solidly blue in the polls and is home to Clinton's vice-presidential running mate, Tim Kaine. The population is also more highly educated and has more black voters than the national average. That is a voting group Trump could lose by 80 points.

To put together any of these winning maps, Trump needs to overcome more than his deficit in the polls and the chaos thrown into his campaign by this weekend's events. He also has regional blocs to divide, long voting histories to rewrite and hostile demographic groups to woo. No easy task for an experienced campaigner.

Is it an impossible one for Donald Trump?