On this alone, one could bring an article of impeachment, and perhaps at some point the House will feel emboldened to do so. However, for now and without precluding any further action, the House must proceed swiftly with two measures.
First, it must pass legislation criminalizing such conduct. The law should explicitly make it illegal to accept opposition research from a foreign government or agent of a foreign government and must require notification to the FBI of any offer of such help. Dare the Republicans to vote against it, to put them on the side of disloyalty and renunciation of U.S. sovereignty.
Second, without precluding impeachment for this or other conduct, the House should pass a resolution condemning the welcoming of interference, reaffirming the obligation to report such conduct, explaining the necessity of protecting the American people’s right to pick their own leaders (can you believe such a statement is needed?) and setting forth the danger of such influence-peddling schemes that reduce anyone stupid enough to take such a meeting as a pawn of a foreign action. Again, let’s see which Republicans vote against it and on what grounds Senate Republicans object to the most basic reaffirmation of our democratic system.
Out on the Democratic presidential primary trail, it would be a fine idea for all candidates (and invite Republican presidential candidate Bill Weld) to sign a statement condemning the president’s remarks, vowing to report immediately any foreign invitations for information on their peers or on the president, and calling for Trump to resign now that he has called into question his loyalty to the United States and ability to uphold his oath. Individual candidates have already begun to condemn Trump, but a joint statement would underscore how far Trump has strayed and would reaffirm that any Democratic candidate is more loyal to the country, and hence more fit to serve.
Proponents of impeachment will argue that this is precisely the sort of conduct that warrants moving forward. But the fact that the Senate would still acquit him means impeachment risks vindicating Trump rather than removing him. However, here’s the test: If Senate Republicans are willing to pass legislation and sign onto the resolution described above, perhaps it would not be a useless exercise for the House to impeach.
Of course, Republicans will excuse Trump, evade the issue, blur the distinction between opposition from a foreign power and domestically sourced opposition, and once more enable his wrongdoing. That attitude likely precludes forcing him out of office before the election, but it fully justifies — in fact demands — his and any Republican incumbents’ removal in the election. They have aligned themselves with the United States’ foes and therefore are not fit to serve.