- 2016 Presidential campaigns netted $1,300M (source: FEC). ($325M/year averaged over 4 years as per @Philipp's comment)
- House: $967M ($484M/year averaged )
- Senate: $507M ($253M/year averaged)
- Total: $2,774M=$2.7B ($1062M=$1T/year averaged)
In reality, spending is slightly less since not 100% of funds is disbursed.
Funding with taxes:
In fiscal year 2015, the federal budget is $3.8 trillion (source, with data they used sourced from OMB).
Roughly 2/3 to 3/4th of that was on medicare, social security, unemployment, labor, education, VA and such (the pie chart under "All Federal Spending" section is best for one-glance view). I'm roughly eyeballing that at ~2.7T-$3T.
As such, if 100% of campaign money raised was spent as part of the federal budget, it would cover less that 0.1% (1/1000th) of said budget, even if we only cover "important spending on the people" and not entire budget.
If you adjust for @Philipp's comment that campaign spending is not annual, we
As per @Philipp's comment, federal spending is an annual figure, whereas campaign spending for 2016 should really be amortized over 4 (pres) and 2 (congress) years. As such, the discrepancy and impact is even more than my original answer stated - campaign spending is 1/3600th of full budget (0.03%) and rises to a whole 0.037% if you only count budget pieces spent on "the people" directly.
Impact is insubstantial in the extreme.