Passport JS has no method 'authenticate'

Node is showing me a weird looking error, and I have been following examples in writing this code but it doesn't work for me. Here is the error.

router.post('/login',passport.authenticate('local', 
                              ^

TypeError: Object function (req, res, next) {
    app.handle(req, res, next);
  } has no method 'authenticate'
    at Object.<anonymous> (/Users/Jasim/Documents/WorkArea/nearby-hashtags/routes/auth.js:34:31)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Module.require (module.js:364:17)
    at require (module.js:380:17)
    at Object.<anonymous> (/Users/Jasim/Documents/WorkArea/nearby-hashtags/app.js:63:12)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
30 Mar 02:11:06 - [nodemon] app crashed - waiting for file changes before starting...

Here is my auth.js

var express = require('express');
var router = express.Router();
var user = express('../models/user');
var passport = express('passport');

router.route('/register')
.get(function(req, res, next) 
{
  res.render('register', { title: 'Register' });
})
.post(function(req, res, next) 
{
    User.register(new User({username: req.body.EmailID, email : req.body.EmailID, name: req.body.username}), req.body.Password, 
        function(err, user)
        {
      if (err) 
      {
          return res.render('register', { user : user });
      }
      passport.authenticate('local')(req, res, function () 
      {
        res.redirect('/home');
      });
        });
});

router.get('/login',function(req, res, next)
{
    res.render('index', {title: 'Login'});
});

router.post('/login',passport.authenticate('local', 
{
    failureRedirect:'/',
    successRedirect:'/home',
    failureFlash: true
}), function(req, res, next){});

router.get('/logout', function(req, res)
{
    req.logout();
    res.redirect('/');
});

module.exports = router;

Please let me know if more information is required.