“It’s going to be a media circus, sure, and we’re ready for that,” said Tim Murtaugh, the communications director for the Trump campaign. He said his war room had been battle tested during the release of the Mueller report, which investigated Russian interference in the 2016 election and ties between Moscow and Mr. Trump’s campaign.

The Trump campaign’s defense efforts will be augmented and amplified by the Republican National Committee. But the committee is also planning to turn up criticism of potentially vulnerable House Democrats in swing districts who have supported the impeachment inquiry , a campaign it calls “Stop the Madness,” which it has backed with more than $10 million in advertising.

Both the Trump campaign and its Republican allies plan to push a single, central message: that Mr. Trump’s conversations with Ukraine were legitimate attempts to root out corruption.

While the impeachment inquiry has undoubtedly dealt some political damage to the president and his re-election effort, his campaign has also reveled in the fund-raising opportunity it provides. According to Mr. Murtaugh, on the day the House voted to endorse the impeachment inquiry, the campaign raised $3 million online.

On the Democratic side , the Democratic National Committee is planning to staff its 30-person response team well before the hearing gets underway, pushing out “what to watch for” lists to reporters and beginning a public character defense of William B. Taylor Jr., the top American diplomat in Ukraine and the first witness scheduled to testify on Wednesday. Democrats anticipate that Republicans will try to criticize him if he offers damning testimony like he did last month in a closed-door hearing.

Democrats have also built a file of old video clips showing how Republican members of Congress have talked about impeachment , ready to publish anything that contradicts statements they may make in the coming days. Democrats used a similar strategy after the release of the Mueller report.

And in an effort to combat the vast and loud Trump surrogate network online, the D.N.C. has been using “DM rooms,” or private group chats on Twitter , to coordinate the response among surrogates by sharing video clips, statements, fact-checks and more.