Washington (CNN) During a face-to-face meeting last week, Senate Majority Leader Mitch McConnell had some blunt advice for President Donald Trump: Stop attacking Senate Republicans.

As the House votes Thursday on a resolution guiding the impeachment process, Trump faces new pressure to keep Republicans on his side as he weathers the political crisis.

But neither he nor his team have offered their allies much in the way of strategy. And their key argument against the impeachment effort -- that it began, illegitimately, without a vote -- was undercut with the Democrats' resolution.

As he faces an escalating impeachment investigation, Trump has ramped up his phone calls to Republicans, at times asking for their advice and expressing disbelief House Democrats will actually impeach him.

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