You can rollover a pension to an IRA.
https://www.irs.gov/pub/irs-tege/rollover_chart.pdf
If you do an indirect rollover, where you get a check from the pension plan and deposit that in the IRA, the pension plan may be required to withhold 20%. If you can't make up the difference, then you have a partial rollover and a partial withdrawal. For example, if you withdraw $50,000 and there is $10,000 withheld, and you get a check for $40,000. You deposit this in the IRA. You now have a $40,000 rollover and a $10,000 withdrawal. The tax on the withdrawal portion will come out around $2500 when you file your tax return. Since you had $10,000 withheld, you will get the other $7500 back as part of your tax refund.
It may be to your advantage to make up the missing funds from other sources. Even possibly a short term bank loan. You have 60 days to send the missing $10,000 to the IRA to be counted as part of the rollover. If you could borrow $10,000 at 8% for 6 months, you would pay $400 in interest, and pay off the loan when the entire $10,000 of withholding is refunded to you. That's $400 of interest instead of $2500 of income taxes.
