The front-runner in Saturday’s election is Susan Wright, who has been endorsed by Donald J. Trump and is the widow of Representative Ron Wright, who died of Covid-19 in February.AUSTIN, Texas — Not long ago, Texas’ Sixth Congressional District seemed to be securely in Republican hands. Ron Wright, a member of the conservative House Freedom Caucus, was poised to advance the G.O.P.’s agenda after he was elected in 2018.But this year Mr. Wright, who had lung cancer, contracted the coronavirus and became the first member of Congress to die from Covid-19. His unexpected death led his wife, Susan Wright, to run for his seat, and she was expected to take her husband’s place in Washington with little pushback.Instead, a field of 23 candidates crowded into Saturday’s special election, all competing for a spot in a likely runoff if no candidate gets more than 50 percent of the vote.Mrs. Wright, long considered the front-runner, is seeking to capitalize on a recent endorsement from former President Donald J. Trump to establish herself as the undisputed favorite among 11 Republicans, some of whom were also hoping to be anointed by the former president.Ten Democrats led by Jana Lynne Sanchez, who ran against Mr. Wright in 2018, are tapping into a reservoir of Hispanic and African-American growth that has stirred hopes among party leaders in a district that Mr. Trump won by only three percentage points in the 2020 election.The Sixth District had been a Democratic stronghold until 1983, when the Democratic incumbent, Phil Gramm, changed party affiliations, turning the district into a reliable bastion of Republican strength for nearly four decades.The race also includes a libertarian and an independent.“It’s pretty crazy,” said Cathy Stein, an independent voter in the Arlington area, referring to the long list of options. “I definitely have a short list now. But I won’t know until I have the ballot in front of me. I’m not a fan of having too many candidates running for the same seat.”Ms. Stein will most likely remain undecided until she shows up to her polling site on Saturday. She said she was looking for a candidate willing to work with others in Washington.The district cuts across three North Texas counties and sprawls along the lower edge of the nation’s fourth-largest metropolitan region, anchored by Dallas, Fort Worth and Arlington.The ultimate outcome of the race could shed new light on Mr. Trump’s continued political hold in Texas, the growth of Hispanic and African-American political power and the impact of the savage pandemic.In endorsing Mrs. Wright, Mr. Trump said in a statement that Mr. Wright voted along party lines during his short tenure in Congress — 96 percent of the time, according to FiveThirtyEight. Before his death on Feb. 7, he was among 139 Republican members of the House to vote against certifying the results of the 2020 presidential election.Former Representative Ron Wright, right, in 2019. His wife, Susan Wright, center, is considered the front-runner for his vacant seat.Susan Walsh/Associated PressBut the election on Saturday could help indicate whether Mr. Trump’s hold on the party took any kind of hit after a mob of his supporters ransacked the Capitol on Jan. 6.“We shouldn’t be afraid of Donald Trump. His endorsement can sometimes backfire,” said Nathalie Rayes, president of Latino Victory, an advocacy group that seeks to strengthen the political power of Latinos.Latinos, who tend to lean Democratic, make up nearly 20 percent of the population in the district, which has made this crowded race more competitive for left-leaning candidates, Ms. Rayes said. Her organization is backing Ms. Sanchez, who lost to Mr. Wright by eight percentage points in the race for the seat in 2018.If elected, Ms. Sanchez would be the first Latina to represent the district.Whoever ultimately wins will join the second-largest congressional delegation in the country, one that will be expanded by two seats next year because of new census data. The delegation now has 36 members — 22 Republicans and 13 Democrats, along with the vacancy in the Sixth District.Whether someone other than Mrs. Wright and Ms. Sanchez can get into the two-person runoff remains unclear, but the likeliest candidate seems to be State Representative Jake Ellzey of Midlothian, a Republican.Mr. Ellzey, a former Navy fighter pilot and a commercial airline pilot who ran against Mr. Wright in the 2018 Republican primary, also brandishes his own high-profile endorsement. He has been supported by Rick Perry, Texas’ longest-serving governor and energy secretary during part of the Trump administration.Although Mr. Perry’s support of Mr. Ellzey puts him at political odds with his former boss in Washington, the former governor is a longtime friend of the congressional candidate.Another Republican contender, Brian Harrison, is a former chief of staff at the Department of Health and Human Services who touts his service in the Trump administration. A website photo shows him standing next to Mr. Trump in the Oval Office.While the Republican candidates offer differing styles and backgrounds, they appear to be fundamentally in agreement in calling for a strong border enforcement, low taxes, gun rights and other G.O.P. priorities. “There are differences in life experiences, but not on the issues,” Craig Murphy, Mr. Ellzey’s campaign spokesman, said.One outlier is Michael Wood, a business owner who has gained attention as an anti-Trump Republican. He has said that the former president bears much of the responsibility for the Capitol riot and that many traditional Republicans are looking for an alternative to Trumpism.The challenge for other Democrats in the race is to topple Ms. Sanchez’s status as the Democratic front-runner and land a spot in the runoff. Leading contenders include Lydia Bean, a teacher and business owner, and Shawn Lassiter, an educator.“It’s anybody’s race at this point,” Ms. Rayes said.Dave Montgomery More