It's a long road to the White House, so The Washington Post polled all 50 states to find out what each candidate needs to do to get there. (Peter Stevenson,Julio Negron,Zoeann Murphy/The Washington Post)

It's a long road to the White House, so The Washington Post polled all 50 states to find out what each candidate needs to do to get there. (Peter Stevenson,Julio Negron,Zoeann Murphy/The Washington Post)

With nine weeks until Election Day, Donald Trump is within striking distance in the Upper Midwest, but Hillary Clinton’s strength in many battlegrounds and some traditional Republican strongholds gives her a big electoral college advantage, according to a 50-state Washington Post-SurveyMonkey poll.

The survey of all 50 states is the largest sample ever undertaken by The Post, which joined with SurveyMonkey and its online polling resources to produce the results. The state-by-state numbers are based on responses from more than 74,000 registered voters during the period of Aug. 9 to Sept. 1. The individual state samples vary in size from about 550 to more than 5,000, allowing greater opportunities than typical surveys to look at different groups within the population and compare them from state to state.

[How the Post-SurveyMonkey poll was conducted]

The massive survey highlights a critical weakness in Trump’s candidacy — an unprecedented deficit for a Republican among college-educated white voters, especially women. White college graduates have been loyal Republican voters in recent elections, but Trump is behind Clinton with this group across much of the country, including in some solidly red states.

The 50-state findings come at a time when the average national margin between Clinton and Trump has narrowed. What once was a Clinton lead nationally of eight to 10 points shortly after the party conventions ended a month ago is now about four points, according to the RealClearPolitics polling average. A number of battleground states also have tightened, according to surveys released from other organizations in recent days.

The Post-SurveyMonkey results are consistent with many of those findings, but not in all cases. Trump’s support in the Midwest, where the electorates are generally older and whiter, appears stronger and offers the possibility of gains in places Democrats carried recently. He has small edges in two expected battlegrounds — Ohio and Iowa — and is close in Wisconsin, Pennsylvania and Michigan, each of which Democrats have won in six consecutive elections.

At the same time, however, Trump is struggling in places Republicans have won consistently and that he must hold to have any hope of winning. These states include Arizona and Georgia, as well as Texas — the biggest surprise in the 50-state results. The Texas results, which are based on a sample of more than 5,000 people, show a dead heat, with Clinton ahead by one percentage point.

Clinton also leads by fewer than four points in Colorado and Florida and is tied with Trump in North Carolina. In Colorado, other polls have shown a larger Clinton lead. In Mississippi, Trump’s lead is just two points, though it’s doubtful that the GOP nominee is in much danger there.

Electoral college advantage for Clinton

In a two-way competition between the major-party candidates, Clinton leads by four points or more in 20 states plus the District of Columbia. Together they add up to 244 electoral votes, 26 shy of the 270 needed to win.

Trump leads by at least four points in 20 states as well, but those add up to just 126 electoral votes. In the 10 remaining states, which hold 168 electoral votes, neither candidate has a lead of four percentage points or better.

View Graphic How our new poll compares with past presidential election results in every state

A series of four-way ballot tests that include Libertarian Party nominee Gary Johnson and Green Party nominee Jill Stein project a somewhat narrower Clinton advantage, with more states showing margins of fewer than four points between the two major-party candidates. But even here, at the Labor Day weekend turn toward the Nov. 8 balloting, the pressure is on Trump to make up even more ground than he has in recent weeks if he hopes to win the White House.

The poll finds Johnson is poised to garner significant support. He is currently receiving at least 15 percent support in 15 states. The libertarian’s support peaks at 25 percent in New Mexico, where he served two terms as governor. He is only four points shy of Trump’s 29 percent standing there. His support in Utah is 23 percent, and in Colorado and Iowa it is 16 percent. Stein has less support in the poll, peaking at 10 percent in Vermont and receiving at least 7 percent support in 10 states.

[Read the full Post-SurveyMonkey results]

Overall, the results reflect Trump’s strategy of maximizing support in older, whiter Midwestern states where his anti-free-trade message and appeals to national identity generally find more fertile ground.

But his struggles elsewhere, including places that have long supported Republicans, illustrate the challenges of that strategy in more diverse states where his stances on immigration and some other positions have turned off Democrats, independents and many Republicans.

Demographic divisions shape the competition

To win the election, Trump must quickly consolidate the Republican vote. With prominent Republicans declaring they will not support Trump and some even announcing they will back Clinton, this represents a major challenge for the GOP nominee. In the Post-SurveyMonkey poll, Clinton is winning 90 percent or more of the Democratic vote in 32 states, while Trump is at or above that level in just 13.

As expected, the Clinton-Trump contest has split the electorate along racial lines. Their bases of support are mirror images: On average, Clinton does 31 points better among nonwhite voters than whites, and Trump does 31 points better among white voters than nonwhites.

The electorate is also divided along lines of gender and education, in many cases to a greater extent than in recent elections. Averaging across all 50 states, Clinton does 14 points better among women than men, and Trump does 16 points better among men than women. Clinton is winning among women in 34 states, and she’s close in six others. Trump leads among men in 38 states, is tied in six and trails in the other six.

It is among college-educated voters, however, where Trump faces his biggest hurdle. In 2012, white voters with college degrees supported Republican nominee Mitt Romney over President Obama by 56-42 percent. Romney won with 59 percent among white men with college degrees and with 52 percent among white women with college degrees.

So far in this campaign, Clinton has dramatically changed that equation. Among white college graduates, Clinton leads Trump in 31 of the 50 states, and the two are about even in six others. Trump leads among college-educated whites in just 13 states, all safe Republican states in recent elections.

Across 49 states where the poll interviewed at least 100 white college-educated women, Clinton leads Trump with this group in 38 states and by double-digit margins in 37. Averaging across all states, Clinton leads by 23 points among white women with college degrees.

Trump’s base among white voters without a college degree remains strong and substantial. He leads Clinton in 43 of the 50 states, and the two are roughly even in five others. She leads among white voters without a college degree in just one state: Vermont.

Overall, Clinton does 19 points better among white college graduates than whites without degrees while Trump does 18 points better among whites without degrees than whites with college educations, on average.

Trump’s challenge in the states that remain close will be to produce significant turnout among white, non-college voters to offset those Clinton margins, but it’s far from clear that there are enough of them to be decisive. Absent that, the GOP nominee must find a way to appeal to these college-educated voters during the final weeks of the campaign.

States and regions shaping the race

Trump’s strength across some of the states in the Midwest is one potential bright spot for the Republican nominee. Clinton’s biggest lead among the contested states in that region is in Pennsylvania, where her margin is just four points. In Wisconsin and Michigan, she leads by a nominal two points, while Trump leads by four points in Iowa and three points in Ohio.

Recent polls by other organizations have indicated that Wisconsin has tightened over the past month. A recent Suffolk University poll in Michigan shows Clinton leading by seven points, and the RealClearPolitics average in Ohio shows Clinton ahead by three points. Overall, among the quintet of Ohio, Michigan, Wisconsin, Iowa and Pennsylvania, Michigan has been the Democrats’ most reliable of the group, always one of the 15 best-performing Democratic states over the past five elections.

The Rocky Mountain West is another area of fierce competition. The Post-SurveyMonkey poll shows Colorado closer than other polls there, with Clinton leading by just two points and the race tied when Johnson and Stein are included. Meanwhile, Clinton and Trump are roughly even in Arizona. In Nevada, Clinton enjoys a lead of five points in head-to-head competition with Trump but by just three points in a four-way test.

Of all the states, Texas provided the most unexpected result. The Lone Star State has been a conservative Republican bastion for the past four decades. In 2012, President Obama lost the state by 16 points. For Democrats, it has been among the 10 to 15 worst-performing states in the past four elections.

The Post-SurveyMonkey poll of Texas shows a dead heat with Clinton at 46 percent and Trump at 45 percent. Democrats have long claimed that changing demographics would make the state competitive in national elections, but probably not for several more cycles.

A comparison of the current survey with the 2008 Texas exit poll (there was no exit poll there in 2012) points to reasons the race appears close right now. Trump is performing worse than 2008 GOP nominee John McCain among both whites and Hispanics, while Clinton is doing slightly better than Obama.

Among men, Trump is doing slightly worse than McCain did eight years ago. The bigger difference is among women. McCain won a narrow majority of women in Texas while Trump is currently below 40 percent. That’s not to say Texas is turning blue in 2016. Given its history, it probably will back Trump in November and possibly by a comfortable margin. But at this stage, the fact that it is close at all is one more surprise in a surprising year.

Emily Guskin contributed to this report.