Congress has decided that the conduct described in the two Articles of Impeachment against Trump constitute "high crimes and misdemeanors" pursuant to Art. II, Sec. IV. Source: The U.S. Constitution.
Since you don't like that I cite Wikipedia, this time, I will cite no less an esteemed "primary source" than the Heritage Foundation itself!
https://www.heritage.org/constitution/#!/articles/1/essays/11/impeachment
The Heritage Foundation says:
"The near-unanimous view of constitutional commentators is that the House of Representatives' 'sole power' of impeachment is a political question and therefore not reviewable by the judiciary. The House is constitutionally obligated to base a bill of impeachment on the standards set out in Article II. (See Article II, Section 4.) However, the fact that the Constitution's text grants the House the 'sole power,' and the fact that such a review is not clearly within the Article III power of the federal judiciary indicate that this responsibility is the House's alone. The Supreme Court has found that the Senate's 'sole power" to try impeachments is not justiciable. Nixon v. United States (1993)."
Taking that thought a little further: Congress alone gets to define what constitutes impeachable conduct. To wit:
https://teachingamericanhistory.org/library/document/articles-of-impeachment-of-andrew-johnson/
"Although most people today assume that 'high Crimes and Misdemeanors' require that the president commit some indictable offense, the history of the phrase suggests a broader meaning. The Constitution invites debate about the scope of impeachment, and those subject to impeachment are most likely to insist on its narrowest application."
The impeachment of Andrew Johnson contained 11 Articles and they were not specifically titled. The headings of "Obstruction of Congress" or "abuse of power" are immaterial. The impeachable conduct is defined with greater specificity therein.
https://www.politico.com/news/2019/12/10/articles-of-impeachment-trump-abuse-obstruction-full-text-pdf-080185