Plenty of Iraqis are hostile to Iranian influence, but Iran has friends in Iraq that are a threat to America:
While Iranian-backed parties are moving to form a government in Baghdad that could force the U.S. to exit the country, they face growing public anger in oil-rich Basra over governance failures.
Iran's efforts to turn Iraq into Lebanon, with Iranian influence too strong to overcome, continues. America must vigorously oppose Iran and support friends in Iraq who oppose Iranian efforts to add Iraq to Iran's collection of Arab scalps that includes Lebanon and Syria, and which hopes to add Yemen and Bahrain too.
With these events we have supporting evidence that the removal of the evil and dangerous Saddam didn't throw Iraq to Iran--leaving Iraq in 2011 so that Iran had a free run at undermining Iraq was the event that threatened to throw Iraq to Iran.
Although it amazes me that the Democratic belated argument that Saddam was a good counter-weight to Iran implied--if not made explicitly--that we should have accepted a dictatorial and brutal Iraq as a price to contain Iran (but that point was made moot in the last administration by the horrible Iran nuclear deal and associated "outreach").
If we stay in Iraq now after the efforts made in the Iraq War and Iraq War 2.0 with troops and with advisors to fight corruption and build rule of law, we can still have a post-Saddam Iraq that rejects Iranian influence to begin rolling back Iran in the region, helps in the fight against jihadis, and strengthens a fragile democracy to be an example to Arabs that there is governance choice other than dictators/monarchs or jihadis.