When unemployment is high, a modest deficit can be beneficial for economic stimulus.
That is not entirely true, and structurally speaking it is the duel-aim of monetary policy to deal with maximum employment and stable prices.
"Modest" deficits is actually becoming more rare the further we go, and in modern times is impacted more by tax cuts benefitting the few the most over increased spending (by year on year number and percentage of GDP on a trend line.) The whole concept of "economic stimulus" largely ends up a political spin machine statement.
But it is still a function of government spending, and what is far more important is structured stimulus for longer term outlooks. Dealing with infrastructure, science, technology improvements, etc. tends to give the biggest returns over time. Something that deals with economic growth paths which is the biggest foundational piece to increased jobs.
It is a bit old school but largely still applies. Government spending and taxation to stabilize the economy during normal economic cycles, often involving deficit spending during recessions to soften the blow of finding the trough and slowing down deficits during expansion to the next peak. It is that politically this rarely happens as economics would suggest it should.
But outside of that circumstance, mainly because spending money and keeping taxes low are both politically popular. Paying for our spending is less popular.
Sort of true, sort of not. Politically it is fair to say treasury promises wins votes. Less contribution to in taxes, more spending from, or some terrible combination of the two.
Our real issue is economics does not subject itself to popularity contests in a manner consistent with political sentiment, and technically "paying for our spending" is speaking to those without understanding economics. More money into the economy is generally how this is handled which puts far more emphasis on the demand for and stability of the US Dollar (because it competes) on a trend line over looking to just the deficit number fiscal year to year.
Besides, also in modern times how our government threatens the debt we issue and/or deals with trade via temper tantrum tariff fights is a bigger influence over the value of the US Dollar. That does not mean our credit rating is not subject to scrutiny over our levels of debt, because it clearly does. But what rattles the markets and the economy more is this back and forth in political fiscal policy wants that tends to stress both the economy and our currency. (I.e. the Fed is always being reactionary with monetary policy since there is such disconnect with political fiscal and trade policy that causes the harm.)
As long as the US Dollar moderately holds its own, and we do not run into serious resource constraints, we might just weather this latest outlook we see. Ultimately GDP growth should be our target, and all policy should be in concert to pull that off while watching where we are in the natural economic cycle.