Just 24 hours after the suit was filed, Republican politicians from 17 states filed in support of Texas, as did a group of conservative lawyers and personalities that included former Alabama judge Roy Moore, who Trump endorsed during his failed bid for the Senate.
Trump himself also sought to join the suit.
Republican congressmen are also seeking to join the action. Rep. Mike Johnson emailed his colleagues Wednesday morning to round up support for a brief to support the suit.
"President Trump called me this morning to express his great appreciation for our effort," Johnson wrote in the email obtained by ABC News. "He specifically asked me to contact all Republican Members of the House and Senate today and request that all join on to our brief."
Since his Nov. 3 defeat, the president and his allies have mounted over 50 lawsuits in state and federal courts that have met with resounding and, at times, scathing defeats. On social media, Trump suggested the Supreme Court would finally give him the hearing he has been seeking.
"The case that everyone has been waiting for is the State's case with Texas and numerous others joining. It is very strong, ALL CRITERIA MET," Trump tweeted Wednesday.
Texas takes the lead
Texas Attorney General Ken Paxton took the lead in filing the lawsuit alleging that four battleground states "exploited the COVID-19 pandemic" to improperly loosen election rules and skew the contest's outcome. The states -- Pennsylvania, Michigan, Wisconsin and Georgia -- all certified following the election that Democrat Joe Biden had secured their electors.
"Their failure to abide by the rule of law casts a dark shadow of doubt over the outcome of the entire election," Paxton said in announcing the legal action. "We now ask that the Supreme Court step in to correct this egregious error."
Paxton has a history of going to court to help Trump's agenda; a year ago he filed briefs with the U.S. Supreme Court supporting Trump's effort to rescind the Deferred Action for Childhood Arrivals, known as DACA, though the effort was ultimately unsuccessful. The lawsuit the Texas Republican filed earlier this week against four swing states appears to be aimed squarely at helping Trump flip the outcome of the presidential contest.
Trump and GOP allies ask to join
In his motion asking to formally join the Texas lawsuit, Trump attorney John Eastman argues that the contest -- which has been certified by all 50 states as a Biden win -- still hangs in the balance. An accompanying complaint offers a fawning and distorted portrayal of Trump's electoral performance, repeating an array of unfounded claims -- but hedging the case about alleged fraud that has been repeatedly rejected in dozens of other post-election legal challenges.
"It is not necessary for [Trump] to prove that fraud occurred," Eastman argues, saying that it is only necessary to demonstrate that the elections "materially deviated" from how state lawmakers intended elections to run.
"By failing to follow the rule of law, these officials put our nation's belief in elected self-government at risk," Eastman writes.
A group of Republican supporters, led by Moore, argued that "Congress certainly did not intend to open the floodgates to allow anyone to vote weeks or months in advance of the federally-established election date, whether in person or by mail or by ballot harvesting or other means which might vary dramatically from one state to another."
But legal experts said the Trump supporters fail to address why the challenge has come now, when the four states made changes to their election plans long before Election Day in order to address the unique challenges posed by the coronavirus pandemic. They said the case is unlikely even to be considered by the Supreme Court, let alone used to reverse the outcome of the presidential contest.
"Jiggery-pokery," critics say
A group of former Republican officials that include former Sen. John Danforth, former Gov. Christine Todd Whitman, and former Sen. and Gov. Lowell Weicker described the case with the term "jiggery-pokery," which means deceitful or dishonest, in their motion against Texas and in support of the four states being sued.
The former GOP officials wrote that the idea of the high court hearing the case makes "a mockery of federalism and separation of powers. It would violate the most fundamental constitutional principles for this Court to serve as the trial court for presidential election disputes."
The justices first must decide whether to accept the case, and could reject it outright, before even considering the merits, experts say. The court could alternatively grant Texas' complaint and move to render an opinion. Legal experts say a full hearing or oral argument are unlikely in such a scenario.
Election law scholar Rick Hasen, a professor at the University of California-Irving Law School, said in his blog that is was "the dumbest case I've ever seen filed on an emergency basis at the Supreme Court."
The case comes less than a week before the Electoral College is set to finalize the selection of the next president.
Historically, the Supreme Court justices have signaled broad deference to states in administering their elections, and an aversion to politicizing the court by interfering in that process.
"It's just simply madness -- the idea of supplanting the vote of the people with partisan legislators is so completely out of our national character that it's simply mad," Sen. Mitt Romney, R-Utah, said Wednesday. "Of course, the president has the right to challenge results in court, to have recounts. But this effort to subvert the vote of the people is dangerous and destructive of the cause of democracy."