There may be a worry that raising the debt ceiling would be an admission that the government is still running at a deficit. Alt-right sites have used the annual April surplus (April usually has a surplus for technical reasons) to post articles like:
"[Bias alert] Trump’s STUNNING budget surplus ignored by media
President Donald Trump has started to drain the swamp in Washington, D.C. — and it’s working.
Trump’s efforts to reduce government spending caused to a huge $184 billion April budget surplus"

Which led readers to think that this temporary spike was a sign that Trump has magically (without a budget) changed the government to no longer adding to the debt. Raising the debt ceiling would puncture that particular illusion.