As long as she keeps the investigations inside the House, the Republican Senate will have no chance to "exonerate" Trump.
Lawrence Tribe, Harvard constitutional law professor, has suggested that, for purposes of censure, Trump could be impeached, tried, and convicted in the House. Of course conviction in the House doesn't carry with it removal from office but it would taint Trump with the blemish of impeachment, conviction and censure that would forever stain his presidency. And, depending on timing, it could encourage other republicans to challenge him for the republican nomination.
After the conviction is announced and had a chance to "mellow" in the public consciousness, the House could decide whether or not to make the impeachment referral to the Senate. If there is strong enough public support for conviction in the states with enough vulnerable republican senators to give dems a substantial majority in the senate, the House should refer the impeachment to the Senate and dare those vulnerable republican senators to defy the will of their constituents!
The dems are making the right moves at this time to test whether or not the courts will uphold their authorities to subpoena witnesses and to enforce those subpoenas (after all, there can be no trial without witnesses). If those authorities are upheld, an impeachment trial strategy should be developed, witnesses identified and the subpoena cannon should be fired!