Sept 5 (Reuters) - The Texas Senate on Tuesday voted overwhelmingly to reject motions to dismiss impeachment charges against Texas Attorney General Ken Paxton as it opened a trial spearheaded by his fellow Republicans that could strip him of his job over allegations of corruption and other wrongdoing.

Paxton, an ally of former President Donald Trump, has been suspended from his post since the Texas House of Representatives voted in May to impeach him on 20 corruption charges including aiding a wealthy political donor and persecuting whistleblowers from his office who accused him of wrongdoing.

His fate rests with the 31-member state Senate, which has the power to remove him after a trial that opened on Tuesday on 16 of those articles of impeachment. The trial is expected to last several weeks. Both chambers of the legislature are controlled by Republicans.

The Senate on Tuesday voted on various pretrial motions. Senators rejected a motion to dismiss all the charges by a vote of 24-6 and voted against additional motions to throw out individual charges.

Paxton, also under investigation by the FBI, has denied wrongdoing and has portrayed the impeachment drive as a political witch hunt. Paxton, 60, has been elected to his post three times despite legal woes that stretch back to 2015, handily winning re-election last year.

As attorney general, he has backed powerful oil and gas interests and pursued restrictions on abortion and transgender rights. He has led Republican state opposition to the policies of Democratic presidents and filed a lawsuit seeking to overturn Trump's 2020 election defeat.

Paxton's impeachment was triggered by his request that House lawmakers approve a $3.3 million settlement he reached with four former staff members who accused him of abuse of office and were subsequently fired. State lawmakers did not act on Paxton's request.

The state House voted 121-23 to impeach him on 20 articles that accused him of improperly aiding a real estate developer named Nate Paul who donated to Paxton, conducting a sham investigation against the whistleblowers in his office, and covering up wrongdoing in a separate federal securities fraud case, among other offenses.

The Senate has 19 Republicans and 12 Democrats. If all the Democrats vote to convict Paxton as expected, nine Republicans would need to join them to reach the two-thirds majority necessary to permanently remove him from office.

Paxton's wife, Angela, is a Republican state senator, but was not allowed to vote or participate in his trial due to concerns over conflict of interest.

The state Senate's impeachment rules committee set aside four charges involving Paxton's private business dealings that House charges said were obstruction of justice and false statements in official records. At the end of the trial on the 16 remaining charges, the Senate could dismiss those four charges or hold a separate trial on them.

The trial could expose a split among the state's Republicans that echoes the national party's divisions over Trump, who is the front-runner for his party's nomination to face Democratic President Joe Biden in the 2024 U.S. election despite facing criminal charges this year in four separate cases.

Jonathan Stickland, who heads a political action committee backed by three billionaire oil tycoons, has vowed to work to ensure that Republicans who oppose Paxton face a well-funded primary opponent in their next election.

That pressure could help Paxton win acquittal, according to Rice University political scientist Bob Stein.

"If senators want to hold onto their seats, let alone do something in the future like run for Congress, they have to watch carefully what they do because of these political donors backing Paxton," Stein said.

Southern Methodist University political scientist Cal Jillson pointed to the lopsided House vote as a sign that Paxton might not hold on to his job.

"There is great security in crowds. The crowd of Republicans that voted to impeach him in the House and those that will likely vote against him in the Senate are going to be harder to punish," Jillson said.

(Reporting by Brad Brooks in Longmont, Colorado; Editing by Will Dunham, Donna Bryson and Andy Sullivan)