How to use EXPECT in a loop foor ssh

Our Linux setup doesn't have keygen configured for password less authentication. Hence I am supposed to use only EXPECT for password less authentication in a shell script.

   /usr/bin/expect<<EOF >> ${LOG_FILE}set timeout 60spawn   sftp ${EWS_USER}@${EWS_HOST}:${TGT_DIR}expect "*?assword:"send "$password\r"expect "sftp>"send "put $local_dir/$line\r"expect "sftp>"send "bye\r"expect EOFEOF        filename=$(basename "$line")        # echo "File Name: $filename"        #Calculate the MD5Sum locally.        local_md5sum=$(md5sum "$line")        #echo "Local MD5Sum: ${local_md5sum}"        #Calculate the MD5sum in remote machine        remote_md5sum=$(ssh ${EWS_USER}@${EWS_HOST} "cd '$TGT_DIR' ; find -name '$filename'  -exec md5sum {} \;"< /dev/null)        #echo "Remote MD5Sum: ${remote_md5sum}"LOCAL_SUM=`echo ${local_md5sum} | awk {'print $1'}`REMOTE_SUM=`echo ${remote_md5sum} | awk {'print $1'}`echo $LOCAL_SUMecho $REMOTE_SUMif [ "${LOCAL_SUM}" != "${REMOTE_SUM}" ]then        echo "SFTP Successfull"else        echo "SFTP Unsuccessfull"fi

I know how to use EXPECT in the below place

sftp ${EWS_USER}@${EWS_HOST} << EOF >> ${LOG_NAME}put ${LOCAL_DIR}/${line} ${TGT_DIR}/${line}EOF

But any idea how to use EXPECT here in the below scenario to make the connection password less?

remote_md5sum=$(ssh ${EWS_USER}@${EWS_HOST} "cd '$TGT_DIR' ; find -name '$filename'  -exec md5sum {} \;"< /dev/null)