diff --git a/transport/grpc/dial.go b/transport/grpc/dial.go
index a6630a0e44..7ed6f23d82 100644
--- a/transport/grpc/dial.go
+++ b/transport/grpc/dial.go
@@ -86,7 +86,8 @@ func Dial(ctx context.Context, opts ...option.ClientOption) (*grpc.ClientConn, e
 		return o.GRPCConnPool.Conn(), nil
 	}
 	if o.IsNewAuthLibraryEnabled() {
-		pool, err := dialPoolNewAuth(ctx, true, 1, o)
+		poolSize := 1
+		pool, err := dialPoolNewAuth(ctx, true, &poolSize, opts)
 		if err != nil {
 			return nil, err
 		}
@@ -108,7 +109,8 @@ func DialInsecure(ctx context.Context, opts ...option.ClientOption) (*grpc.Clien
 		return nil, err
 	}
 	if o.IsNewAuthLibraryEnabled() {
-		pool, err := dialPoolNewAuth(ctx, false, 1, o)
+		poolSize := 1
+		pool, err := dialPoolNewAuth(ctx, false, &poolSize, opts)
 		if err != nil {
 			return nil, err
 		}
@@ -137,7 +139,7 @@ func DialPool(ctx context.Context, opts ...option.ClientOption) (ConnPool, error
 		if o.GRPCConn != nil {
 			return &singleConnPool{o.GRPCConn}, nil
 		}
-		pool, err := dialPoolNewAuth(ctx, true, o.GRPCConnPoolSize, o)
+		pool, err := dialPoolNewAuth(ctx, true, nil, opts)
 		if err != nil {
 			return nil, err
 		}
@@ -174,7 +176,23 @@ func DialPool(ctx context.Context, opts ...option.ClientOption) (ConnPool, error
 }
 
 // dialPoolNewAuth is an adapter to call new auth library.
-func dialPoolNewAuth(ctx context.Context, secure bool, poolSize int, ds *internal.DialSettings) (grpctransport.GRPCClientConnPool, error) {
+func dialPoolNewAuth(ctx context.Context, secure bool, poolSize *int, opts []option.ClientOption) (grpctransport.GRPCClientConnPool, error) {
+	authGRPCOpts, err := AuthGRPCOptions(opts, poolSize)
+	if err != nil {
+		return nil, err
+	}
+	return dialContextNewAuth(ctx, secure, authGRPCOpts)
+}
+
+// AuthGRPCOptions is an adapter converting []option.ClientOption to
+// cloud.google.com/go/auth/grpctransport.Options. If a non-nil
+// poolSizeOverride pointer is provided, it will be used instead of the
+// option.WithGRPCConnectionPool value in opts.
+func AuthGRPCOptions(opts []option.ClientOption, poolSizeOverride *int) (*grpctransport.Options, error) {
+	ds, err := processAndValidateOpts(opts)
+	if err != nil {
+		return nil, err
+	}
 	// honor options if set
 	var creds *auth.Credentials
 	if ds.InternalCredentials != nil {
@@ -220,13 +238,16 @@ func dialPoolNewAuth(ctx context.Context, secure bool, poolSize int, ds *interna
 		defaultEndpointTemplate = ds.DefaultEndpoint
 	}
 
-	pool, err := dialContextNewAuth(ctx, secure, &grpctransport.Options{
+	if poolSizeOverride == nil {
+		poolSizeOverride = &ds.GRPCConnPoolSize
+	}
+	return &grpctransport.Options{
 		DisableTelemetry:      ds.TelemetryDisabled,
 		DisableAuthentication: ds.NoAuth,
 		Endpoint:              ds.Endpoint,
 		Metadata:              metadata,
 		GRPCDialOpts:          prepareDialOptsNewAuth(ds),
-		PoolSize:              poolSize,
+		PoolSize:              *poolSizeOverride,
 		Credentials:           creds,
 		ClientCertProvider:    ds.ClientCertSource,
 		APIKey:                ds.APIKey,
@@ -251,8 +272,7 @@ func dialPoolNewAuth(ctx context.Context, secure bool, poolSize int, ds *interna
 		},
 		UniverseDomain: ds.UniverseDomain,
 		Logger:         ds.Logger,
-	})
-	return pool, err
+	}, nil
 }
 
 func prepareDialOptsNewAuth(ds *internal.DialSettings) []grpc.DialOption {
diff --git a/transport/grpc/dial_test.go b/transport/grpc/dial_test.go
index 63b0a1901f..e70dbd149e 100644
--- a/transport/grpc/dial_test.go
+++ b/transport/grpc/dial_test.go
@@ -16,6 +16,7 @@ import (
 	"github.com/google/go-cmp/cmp"
 	"golang.org/x/oauth2/google"
 	"google.golang.org/api/internal"
+	"google.golang.org/api/option"
 	"google.golang.org/grpc"
 )
 
@@ -38,15 +39,15 @@ func TestDial(t *testing.T) {
 
 func TestDialPoolNewAuthDialOptions(t *testing.T) {
 	oldDialContextNewAuth := dialContextNewAuth
-	var wantNumOpts int
-	var universeDomain string
+	var wantNumDialOpts int
+	var wantUniverseDomain string
 	// Replace package var in order to assert DialContext args.
 	dialContextNewAuth = func(ctx context.Context, secure bool, opts *grpctransport.Options) (grpctransport.GRPCClientConnPool, error) {
-		if len(opts.GRPCDialOpts) != wantNumOpts {
-			t.Fatalf("got: %d, want: %d", len(opts.GRPCDialOpts), wantNumOpts)
+		if len(opts.GRPCDialOpts) != wantNumDialOpts {
+			t.Fatalf("got: %d, want: %d", len(opts.GRPCDialOpts), wantNumDialOpts)
 		}
-		if opts.UniverseDomain != universeDomain {
-			t.Fatalf("got: %q, want: %q", opts.UniverseDomain, universeDomain)
+		if opts.UniverseDomain != wantUniverseDomain {
+			t.Fatalf("got: %q, want: %q", opts.UniverseDomain, wantUniverseDomain)
 		}
 		return nil, nil
 	}
@@ -55,34 +56,31 @@ func TestDialPoolNewAuthDialOptions(t *testing.T) {
 	}()
 
 	for _, testcase := range []struct {
-		name        string
-		ds          *internal.DialSettings
-		wantNumOpts int
+		name               string
+		ds                 []option.ClientOption
+		wantUniverseDomain string
+		wantNumDialOpts    int
 	}{
 		{
-			name:        "no dial options",
-			ds:          &internal.DialSettings{},
-			wantNumOpts: 0,
+			name: "no dial options",
+			ds:   make([]option.ClientOption, 0),
 		},
 		{
-			name: "with user agent",
-			ds: &internal.DialSettings{
-				UserAgent: "test",
-			},
-			wantNumOpts: 1,
+			name:            "with user agent",
+			ds:              []option.ClientOption{option.WithUserAgent("test")},
+			wantNumDialOpts: 1,
 		},
 		{
-			name: "universe domain",
-			ds: &internal.DialSettings{
-				UniverseDomain: "example.com",
-			},
-			wantNumOpts: 0,
+			name:               "universe domain",
+			ds:                 []option.ClientOption{option.WithUniverseDomain("example.com")},
+			wantUniverseDomain: "example.com",
 		},
 	} {
 		t.Run(testcase.name, func(t *testing.T) {
-			wantNumOpts = testcase.wantNumOpts
-			universeDomain = testcase.ds.UniverseDomain
-			dialPoolNewAuth(context.Background(), false, 1, testcase.ds)
+			wantNumDialOpts = testcase.wantNumDialOpts
+			wantUniverseDomain = testcase.wantUniverseDomain
+			poolSize := 1
+			dialPoolNewAuth(context.Background(), false, &poolSize, testcase.ds)
 		})
 	}
 }