Texas Attorney General Ken Paxton has ousted incumbent Senator John Cornyn in the state's highly-watched Republican Senate primary.

Paxton, 63, steamrolled Cornyn, 74 in the runoff race Tuesday night after securing a campaign-altering endorsement from President Donald Trump last week. 

Paxton was thumping Cornyn by 28 percentage points with most precincts reporting on Tuesday evening. It amounts to a shattering end to Cornyn's long political career after issuing sparing disagreements with Trump over the last decade.

'I've always supported the Republican ticket and I intend to do so again in this general election,' the Senator said after conceding the race. 

Cornyn, who failed to secure the endorsement after working months for it, has represented Texas in the Senate since 2002. 

The end of his 23-year run comes as Trump continues to put his indelible imprint upon the Republican Party, exacting retribution among those showing even the slightest sign of disloyalty. 

The longtime Texas Senator criticized Trump's response to the COVID-19 outbreak in 2020, has slammed Trump's behavior before the January 6 Capitol Riot and voted against Trump's gambits to prevent the certification of Joe Biden's victory.

Paxton's victory means he will compete in a heated general election against 37-year-old Democratic candidate James Talarico.

Serving as Texas Attorney General since 2015, Paxton is a close Trump ally who has backed many of the President's most audacious projects, including a 2020 Supreme Court case to nullify Joe Biden's election victory. 

He has also been publicly shamed by his estranged wife for infidelity, even as he's shacked up with his mistress in a tony Dallas suburb. 

Paxton has spent a decade dogged by ethical and legal troubles, including a securities fraud indictment, impeachment, and allegations of bribery - surviving it all.

'He's gotten away with so much for so long,' Cornyn told CNN this week. 'He is an embarrassment.'  

None of that scared away Trump, who places personal loyalty above all else. 

'TEXAS, REMEMBER! Ken Paxton was a GREAT Attorney General, probably the best in the Country. He was also very loyal to your favorite President, ME,' Trump posted on social media this week.

Senate Republican leadership worked for months to get the President to endorse Cornyn. The leaders reportedly wanted to avoid a messy and expensive primary between two Republicans - though that is exactly what happened. 

Roughly $130 million has been spent on ads in the Republican-on-Republican Texas primary, according to AdImpact, with Cornyn easily outspending his challenger.

Cornyn's late-stage effort to appease the President also proved unsuccessful. 

The Senator offered a bill to rename a highway after Trump and even flipped his long-held position on the filibuster after increasing pressure from the White House. 

Trump did not formally endorse Paxton until a week ago. His former campaign manager Chris Lacivita worked for Cornyn while the head of the President's political operation, James Blair, backed Paxton, creating a rare divide among Trump's tight-knit team. 

Cornyn's defeat is another scalp for the President's team that has upended several of Trump's GOP targets.

Congressman Thomas Massie and Senator Bill Cassidy - both Republicans who drew Trump's ire - were defeated in their recent primary elections after the President endorsed their opponents. 

Trump also saw that state-level lawmakers in Indiana were defeated after they defied the President and did not back his redistricting plan. 

The President's allies were quick to celebrate the victory of their preferred candidate.