Can I make a contribution to my existing IRA to reduce my federal tax due? How much would I have to contribute?

[ChristyW]

It's possible. Traditional IRA contributions are an above-the-line deduction and may directly reduce your taxable income. This means it can reduce your reported wages, reducing your taxable income. For some incomes, this might allow you to qualify for other deductions and credits due to a lower adjusted gross income (AGI).

If you (or your spouse, if filing a joint tax return) are covered by an employer-sponsored retirement plan, there is a phase-out range.  Depending on your income, you may only deduct part or even none of the IRA contribution.

Roth IRA contributions are not deductible.

How much of my Traditional IRA contribution is deductible? see:  https://ttlc.intuit.com/replies/3301534