Political conventions are echo chambers designed to generate feelings of invincibility, sending forth the party faithful with a spring in their steps and hope in their hearts. Who would want to be a wet blanket at such moveable feasts?

Steve Munisteri would. Although he calls himself “the eternal optimist,” he respects reality, which nowadays is not conducive to conservatives’ cheerfulness. He served as chairman of the Texas Republican Party from 2010 to 2015 because he discerned “a seismic shift in demographics” that meant his state could “turn Democratic sooner than most people thought.”

The fact that Republicans have won every Texas statewide office since 1994 — the longest such streak in the nation — gives them, he says, “a false sense of security.” In 2000, Republican candidates at the top of the ticket — in statewide races — averaged about 60 percent of the vote. By 2008, they averaged less than 53 percent. And Republican down-ballot winners averaged slightly over 51 percent.

Texas is not wide open spaces filled with cattle and cotton fields. Actually, it is 84.7 percent urban, making it the 15th most urban state. It has four of the nation’s 11 largest cities — Houston, San Antonio, Dallas and Austin. Texas’ growth is in its cities, where Republicans are doing worst.

Dallas has gone from solidly Republican to solidly Democratic. A recent poll showed Harris County (Houston), which is 69 percent minority, with a majority identifying as Democrats. The San Antonio metropolitan area is about three-quarters minority. Travis County (Austin, seat of the state government, the flagship state university and a burgeoning tech economy attracting young people) voted 60.1 percent for Barack Obama in 2012.

Asian-Americans, Texas’ fastest-growing minority by percentage, were 3 percent of Texans in 2000 and 4.3 percent in 2010. They are projected to be more than 8 percent in 2040.

In the 2014 gubernatorial election, Hispanics were 25 percent of Texas’ registered voters but only 19 percent of turnout. Two years later, Hispanics are 29 percent of registered voters. Now, suppose the person at the top of a Republican national ticket gives Hispanics the motivation to be, say, 25 percent of turnout. Although it is, Munisteri says, “theoretically possible” for Texas Republicans to win by increasing the white vote, this “political segregation” is, aside from being morally repulsive, politically “a sure-fire long-term losing proposition.”

The “blue wall” — the 18 states and the District of Columbia that have voted Democratic in at least six consecutive presidential elections — today has 242 electoral votes. Texas, which is not a brick in this wall, has 38 electoral votes. After the 2020 census, it probably will have 40, perhaps 41. Were Texas to become another blue brick, the wall — even if the 2020 census subtracts a few electoral votes from the  current 18 states — would have more than the 270 votes needed to elect a president.

Since 1994, when it passed New York (which has now sunk below Florida to fourth place), Texas has been the nation’s second most populous state. Munisteri notes that it is the Republican Party’s only large “anchor state.” The Democratic Party has two — California and New York, with a combined 84 electoral votes. Or three, if you count Illinois (20 electoral votes), which in the last four presidential elections has voted Democratic by an average of slightly more than 16 points.

Munisteri’s conservative credentials are unassailable. He was a precociously conservative teenager — a member of Young Americans for Freedom in high school in 1976 — when Ronald Reagan was trying to wrest the Republican nomination from President Gerald Ford. Munisteri, now working with the Republican National Committee, became a Reagan volunteer and had an exhilarating experience: Reagan, having lost eight of the first nine primaries, revived his candidacy by winning all of Texas’ 100 convention delegates.

Munisteri’s politically formative years were the conservative movement’s salad days — the late 1970s, and 1980s, when many conservatives acquired a serene certainty that this is and always will be a center-right country. Munisteri, however, is “a numbers guy,” so serenity is illusive.

He notes that beginning with Franklin Roosevelt’s first victory in 1932, Democrats won seven of nine presidential elections, and if they had succeeded in their effort to enlist Dwight Eisenhower as a Democrat they probably would have won nine in a row. Trends can be reversed but until they are, Republicans risk protracted losing in a center-left country, which America now is, and in a purple Texas, which soon could be.

© 2016, Washington Post Writers Group