Run a sed command depending on a variable

I am trying to run a variable sed command depending on user input:

#!/bin/bash

ACTION=$1

if [ "wp" == "$ACTION"  ]
then
   MODIFIEDCONF='sed -i -e "/#Begin wp redirect/,/#End wp redirect/d" /root/test-conf'
else
   MODIFIEDCONF='sed -i -e "/#Begin ghost redirect/,/#End ghost redirect/d" /root/test-conf'
fi

RESULT=$($MODIFIEDCONF)

But I am getting the error:

sed: -e expression #1, char 1: unknown command: `"'

How do I fix the error? Or is there a better way to do it?