JSON parseError with HTTP Status: 401 Authorization Required when trying to get Access_token

nodejs

#1

From the post of https://api.twitter.com/oauth/authenticate I got the oauth_token and oauth_verifier

var url_parts = url.parse(req.url, true);
var query = url_parts.query;
const p=querystring.stringify(query);

p is a query string now containing oauth_token and oauth_verifier . Next to exchange the token for a access_token when I post to https://api.twitter.com/oauth/access_token

 T.get('https://api.twitter.com/oauth/access_token?'+p, params, function (err, req, res) {
    console.log(err);
  })

it shows JSON parseError with HTTP Status: 401 Authorization Required
What am I doing wrong?