request.js fails where CURL succeeds for GET request with Authorization header

I can make a GET request with an Authorization header from curl but not from request or https in Node.js. The server returns status 200 with curl but 500 with request or https. How might the call from request or https be different from curl? How might the server be reading them differently?

The following cURL succeeds from command line:

curl -H "Authorization:  Bearer abc123def456" https://api.domain.com/path/to/resource

But the same request fails with request.js in Node

var options = {
  type: 'get',
  url: "https://api.domain.com/path/to/resource",
  headers: {
     "Authorization": " Bearer abc123def456" 
  }
}
request(options, function (err, response, body) {
  assert.equal(response.statusCode, 200) ; // 500 internal error
})

The following also fails with request.js using the auth option:

var options = {
  type: 'get',
  url: "https://api.domain.com/path/to/resource",
  auth: {
    "bearer": "abc123def456" 
  }
}
request(options, function (err, response, body) {
  assert.equal(response.statusCode, 200) ; // 500 internal error
})

It also fails when using https without request.js:

var options = {
  host: 'api.domain.com',
  port: 443,
  path: '/path/to/info',
  method: 'GET',
  headers: {
    "Authorization": " Bearer abc123def456"
  }
}
var req = https.request(options, function (res) {
  res.setEncoding('utf8');
  res.on('end', function () {
    assert.equal(res.statusCode, 200) // 500 internal error
  })
});

req.on('error', function (e) {
  console.log('problem with request: ' + e.message);
});

req.end();

But the curl requests succeeds if shelled out from Node:

exec("curl -H "Authorization:  Bearer abc123def456" https://api.domain.com/path/to/resource", function (error, stdout, stderr) {
  var obj = JSON.parse(stdout) // successfully retrieved and parsed
});

request-debug gives the following info:

{ request: 
   { debugId: 1,
     uri: 'https://api.domain.com/path/to/resource',
     method: 'GET',
     headers: 
      { host: 'api.domain.com',
        authorization: 'Bearer abc123def456' } } }

via prototype