[Help-bash] copy files w

[Val Krem]

Hi all,

I have several files with the same  extension name(*.txt). I want to have   
copy of these files by attaching a suffix to each of the files. Example 
test1.txt should be copied to test1_new.txt. The suffix to be added in all 
files is the same. I tried using this but did not work.

ls *.txt | xargs -I {} cp {} {}_new.txt

test.txt should be test_new.txt
but I got test.txt_new.txt

what should I do to make work?

Thank you in advance