WASHINGTON — Congressional Republicans, not resting with the Internal Revenue Service scandal, are moving to broaden the matter to an array of tax malfeasances and “intimidation tactics” they hope will ensnare the White House.

Republican charges range from clearly questionable actions to seemingly specious allegations, and they grow by the day. On Friday, lawmakers sought to tie the I.R.S. matter to the carrying out of President Obama’s health care law, which will rely heavily on the agency. Whether they succeed holds significant ramifications for Mr. Obama, who will soon know if he is dealing with a late spring thunderstorm that may soon blow over or a consuming squall that will leave lasting damage.

Representative Dave Camp, Republican of Michigan, the usually mild-mannered chairman of the House Ways and Means Committee, set the tone Friday at Congress’s first hearing on the targeting of conservative groups by the I.R.S., laying out details, from the alleged threatening of donors to conservative nonprofit groups to the leaking of confidential I.R.S. documents.

In that context, he said, the screening of Tea Party groups for special scrutiny was not the scandal itself but “just the latest example of a culture of cover-ups — and political intimidation — in this administration.”