The ad wars to sway key votes over allowing witnesses to testify in the U.S. Senate impeachment trial are already underway, with dueling sides of the debate taking to the airwaves to swing the outcome of the upcoming vote.
A group of anti-Trump Republicans is launching new TV ads set to start running on Thursday morning, backed by a six-figure ad buy, to make the case for impeachment witnesses - as the Senate is expected to weigh the critical vote later this week.
Republicans for Rule of Law are airing the series of ads across all cable news networks in six states, plus Washington, D.C, on Thursday and Friday. The targeted states are home to four key GOP senators: Lisa Murkowski of Alaska, Mitt Romney of Utah, Susan Collins of Maine, and Lamar Alexander of Tennessee, as well as Arizona and Colorado, which are home to two vulnerable Republicans up for re-election in 2020, Sens. Martha McSally and Cory Gardner.
"Many Republicans – and a large majority of Americans – now agree with us. And this week, after major revelations from Lev Parnas and Ambassador John Bolton, it’s clearer than ever why," said Chris Truax, a spokesperson for Republicans for the Rule of Law, in a statement to ABC News. "Now it’s decision time and Senate Republicans will come face-to-face with their constitutional responsibilities this Friday when they vote on calling witnesses."
"They can honor their oath to do impartial justice and vote for transparency and openness. Or they can shove their fingers in their ears and try to hide the facts from both themselves and their constituents," Truax continues. "America deserves to see all the evidence. If that changes some minds, whether in the Senate or the public, so be it."
One of those targets, Gardner, who has been quiet during the trial, signaled Wednesday he does not want hear from more witnesses.
"I do not believe we need to hear from an 18th witness," he told Colorado Politics. "I have approached every aspect of this grave constitutional duty with the respect and attention required by law, and have reached this decision after carefully weighing the House managers and defense arguments and closely reviewing the evidence from the House, which included well over 100 hours of testimony from 17 witnesses."
The ads are part of a $1 million campaign which has focused on promoting a fair and full Senate impeachment trial over the past few weeks, according to the group, and are similar to ones that have already aired. The latest ads will cycle through CNN, MSNBC, CNBC, and Fox News every hour from 5 a.m. until midnight on Thursday.
On Friday, the ads will air across the morning shows and then again every hour on each of the networks. The TV ads will also be accompanied by a digital ad campaign in those target states and D.C., along with digital billboards up through Sunday.
But there are also ads on the airwaves that seek to pressure the same group of undecided senators to vote against allowing witnesses.
The conservative outside group, Club For Growth, is out with a new TV ad Wednesday targeting Romney for potentially voting for witnesses to testify in the Senate impeachment trial.
"There's Mitt Romney threatening to vote with Democrats again to trot out spotlight-seeking blowhards who will trash President Trump on the witness stand," the ad begins, showing b-roll of John Bolton and Lev Parnas over "spotlight-seeking blowhards."
The ad then pivots to attacking the Biden family - asking if Romney "wants to know the truth, what about the Bidens" - and ultimately calls for Joe Biden's son, Hunter, to take the stand.
This isn't the first time Club for Growth has taken aim at Romney, last October, the group put out an ad attacking the former Republican nominee for president for supporting Democrats as they pushed for impeachment.
The new ad will run from Jan. 30 to Feb. 1 on Fox News in Salt Lake City and Washington, D.C.
The clash over impeachment witnesses isn't only dividing partisan lines, but is splintering the GOP, after Majority Leader Mitch McConnell, speaking to Republican senators in a closed-door meeting Tuesday evening, said he did not yet have the votes to block a vote to consider witnesses.
Despite the trial entering a new phase on Wednesday, when senators began up to 16 hours of questioning about the charges against Trump, the focus on Capitol Hill continues to be on the question of witnesses after the New York Times report seemed to outline, at least in part, Bolton's testimony if he was subpoenaed to appear.
But the newest slate of ads in the impeachment saga come as Trump is applying political pressure on Republican senators to fall in line. In a series of tweets Wednesday morning, Trump impelled the caucus to vote against calling new witnesses.
A senior White House official told ABC News that the president's defense team still believes they will be able to defeat the measure to call witnesses.
"It's still a hard vote, but we are working hard. It's a long time until Friday," the official said.
ABC News' Mary Bruce, Trish Turner, Jon Karl and Benjamin Siegel contributed to this report.