How do I improve my code so that it only accounts for letters and not punctuation

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Python

I am having difficulty figuring out how to only have letters and no punctuation
this is my code:

import re
def is_palindrome(pal):
    newStr =''
    for i in range(0,len(pal)):
        if pal[i] != ' ':
            newStr = newStr + pal[i]

    print(newStr.lower())

    
    if len(pal) <= 1:
        return True
    else:
        return pal[0] == pal[-1] and is_palindrome(pal[1:-1])

print(is_palindrome("Able was I ere I saw Elba"))
print(is_palindrome("Too bad--I hid a boot"))
print(is_palindrome("Do geese see God"))
print(is_palindrome("Murder for a jar of red rum"))
print(is_palindrome("Drab as a fool, aloof as a bard"))
print(is_palindrome("Norma is as selfless as I am, Ron"))
print(is_palindrome("Gateman sees name, garageman sees name tag"))
print(is_palindrome("A man, a plan, a canal--Panama"))
print(is_palindrome("Go deliver a dare, vile dog"))
print(is_palindrome("Go Hang a Salami! I'm a Lasagna Hog"))
print(is_palindrome("I am Happy"))
print(is_palindrome("The car went over the speed limit"))
print(is_palindrome("Coding is fun"))
print(is_palindrome("Happy go Lucky"))
print(is_palindrome("This is not a palindrome"))
print(is_palindrome("Amazon Prime Shipping"))
print(is_palindrome("A picture is worth a thousand words"))
print(is_palindrome("iPhone's are great"))
print(is_palindrome("The weather outside is nice"))
print(is_palindrome("Last one"))

What I have tried:

the output I get is:

ablewasiereisawelba
False
toobad--ihidaboot
False
dogeeseseegod
False
murderforajarofredrum
False
drabasafool,aloofasabard
False
normaisasselflessasiam,ron
False
gatemanseesname,garagemanseesnametag
False
aman,aplan,acanal--panama
False
godeliveradare,viledog
False
gohangasalami!i'malasagnahog
False
iamhappy
False
thecarwentoverthespeedlimit
False
codingisfun
False